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Author Topic: ATEC Problems  (Read 4385 times)
NJT5049
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« on: May 07, 2009, 08:35:44 AM »

Hi all
I've had a problem with my ATEC I cant seem to resolve. THis is going back about a year now...
It all started when I parked the coach at a remote location during the winter. THe batteries had gone flat, they were removed for charging. Things went to hell when I reconnected everything. It seems that I connected the 12v positive for the ATEC to ground. When I flipped on the master I made smoke in the battery bay.
I've since replaced the ATEC, the key pad for shifting with a replacements from Nimco. The coach starts, I get a check transmission lite, she will move, shift thru the 'gears' once correctly once. After that all shift points are late. The error code I get is a TPS error.
Now the TPS I've checked. I think butch or JR said it should range from 500 - 1500 ohm. I've reset it so I get 500 ohm but only get as much as 1100 ohm full throttle. I had seen check engine light periodically previously so it is suspect.
I've replace or checked all fuses, the wiring harness as much as I can check it is intact.
I've contacted Luke for a replacement TPS and got the wrong part. It seems New Jersey Transit swapped it out years ago. The 'new' replacement part is $600 bucks. OMG lol
She's a 87' MCI9 New Jersey Transit. 6V92 Allison 740RT (ithink) Transmission, running a DDEC I.
Anyone have any suggestions?
-Tom
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NJT5047
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« Reply #1 on: May 07, 2009, 09:22:54 AM »

Hi Tom.  The saga continues I see.   
If you're setting a TPS code, the TPS is suspect.  Or the TPS wiring. 
What engine code was setting?   I remember the problem, but the details.....??   The DDEC and ATEC codes may give you some ideas.   
Are you setting the TPS code in the ATEC or DDEC ECM?
The VSS located on the transmission could be intermittant.  That would cause a shift problem.  The wires are probably hanging loosely above the VSS.  Located on the LH front corner of the transmission.   Should also set a VSS code?   
IF DDEC code also indicated a bad TPS, replacement of the TPS might solve your problem.   I sure hope so after spending $600 bucks.   Either way, it will rule out the TPS... Huh 
I believe you'll receive a complete accelerator assembly. 
Post the results when you get the new TPS installed.   
One other item to check would be to look for linear resistance at the DDEC ECM.   I'd have to check, but I believe the ATEC gets the TPS signal from the DDEC ECM.
Damaged wiring, intermittant fuses in the battery compartment and I'm sure sundrous other expensive items could cause your problem. 
Butch has a SM for your transmission.  I'm planning on getting one..but??? 
NOW we're really going to miss Sammy! 
JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

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« Reply #2 on: May 07, 2009, 09:40:37 AM »

DO YOU GET idle and WOT (WIDE OPEN THROTTLE) on the engine in neutral ??

If not then check -->

The TPS for my DDEC-II  is 2500 ohms between the A-C terminals - The B-C and A-C terminal should vary between (100-600) at low end (1800-2200) at the high end

What your really interested in is that
#1 the voltage between PIN A of the TPS (SENSOR RETURN and PIN C (+5 Volts  supply) is TRUELY 5 volts
#2 the voltage between PIN A of the TPS (SENSOR RETURN) and PIN B (Throttle Signal) is about 4.25 at idle and .5 volts at WOT (WIDE OPEN TROTTLE)

If #1 and #2 are true - THEN CHECK IT AT THE DDEC PIN (not sure what pin on a DDC-1)



BUT YOU SAY THE PROBLEM IS AN ATEC ERROR not a constant DDEC error -

then I suspect it's the INTERFACE DEVICE BETWEEN THE DDEC TPS and THE ATEC
AKA DDEC/TECL INTERFACE DEVICE - I'll include a SIMPLE VERSION of the device that I have on my RTS DDEC-II to ATEC - IT's OEM FACTORY - housed in a little black box about the size of a DECK Of CARDS - It's a little device to isolate and share the TPS sigmal between the ATEC and the DDEC

on DDEC-ii (probably DDEC-III and IV) -  the TPS signal from the DDEC to the ATEC comes from a DDEC connection other than the TPS input -  it's called the PWM circuit 908 pin J3 (It is Similar to the TPS input ??) - I know a little wierd but ??  -- It goes via the interface box  to feed the ATEC TPS input pin 2P   

SEE INCLUDED POST

Pete RTS/Daytona  clear as mud - call me ...386..672.0571
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« Reply #3 on: May 07, 2009, 01:38:47 PM »

When you say, "Key Pad for shifting" is this a push button pad with R, 1,2,3, D on it?   If so, wouldn't the tranny be a 741?  I thought the 740's had a t-handle for shifting.

Bill
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« Reply #4 on: May 07, 2009, 07:01:17 PM »

 Tom;
 Welcome to the board! I have the same type coach,as well. You should have a 748 tranny in your unit. JR is the one that will probably benefit you greatly on this unit. He has certainly been a great help to me! What state do you live in?
Bill
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« Reply #5 on: May 07, 2009, 08:09:56 PM »

When you say, "Key Pad for shifting" is this a push button pad with R, 1,2,3, D on it?   If so, wouldn't the tranny be a 741?  I thought the 740's had a t-handle for shifting.

Bill

Tom's trans is an HT748R.   That's the transmission used in all '87 NJT MC9s.  It is an ATEC with the push button shift pad just like yours.

Tom, the TPS is wired directly to the DDEC ECM.  J1A connector. 
Pin H3 in J1A should have 5 volts.   
Pin C2 in J1A is signal from TPS and will be something less than 5 volts. 
Pin K1 in J1A is TPS ground.   

The TPS plug under the drivers floor will be connected as follows: 
A=K1 (ground), 
B=C2 (signal),   
C=H3 (5 volts).

If your TPS is the fault, you should set a DDEC code '21' or '22'.   What DDEC codes are you setting?
An ATEC TPS code is the same as the DDEC ECM...'21', although I believe this is only applicable for HT741 trans with a TPS mounted remotely on the throttle linkage...such as Bill has.   If your ATEC reads a code '21', but the DDEC doesn't, the wiring between the ATEC and DDEC may be at fault. 
The DDEC 1 dx guide does not offer a resistance range.  It suggests using a 'DDL' reader...which we ain't got.  It counts pulses.  Try using Pete's reference.  May be the same TPS resistance for all DDECs?   
It doesn't appear that DDEC 1/ATEC use an interface.  Looks like the two ECMs communicate directly.   This may be inaccurate...but I have both schematics of the trans and DDEC and they only share a few wires.  The VSS is also processed by the DDEC. 
The wiring DDEC/ATEC connections are inside the upper rear bay...in that crap hole that is typical of NJT MC9s.  Mine appears to be in good condition, but moving them around scares the poop out of me.  Old wiring really doesn't like to be molested. 
Back to those fuse cases in the battery box...I've had an ongoing intermittant issue with the fuse holders and fuses.
They should all be replaced really.  But, it's one of those things that I know how to quickly resolve.  Still, the "Check Transmission' light has some pucker factor when it lights up way off from home! 
Have you had any kneeling, high idle, or other electrical issues?   These all interconnect with the transmission, although they don't set codes...they may if the DDEC senses speed when a limiter is 'on'...
I'd be rechecking the DDEC and ATEC for codes.  Remember that unlike a DDEC II, if you pull the fuse on a DDEC 1, you cleared the memory.   So make the codes set and read both ATEC and DDEC codes.   See what you get. 
If your windshields leak, you may well have a bad TPS.  Water running off the center of the dash drips on them...screws them up.  NJT also hosed out the floors regularly. 
Still, IF the DDEC isn't seeing TPS codes, the TPS probably ain't the problem. 
Until you re-read the codes on both units, the only other thoughts I have would focus on what electrical work was done on the coach prior to the onset of the problem?   
BTW, Butch has the resistance for a DDEC 1 TPS.  He checked his when his bus was acting up.   I can check mine too and see what it looks like.  Have to pull the spare tire out to access the connector, but that ain't much of a problem.   
JR 

   
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

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« Reply #6 on: May 08, 2009, 05:21:25 AM »

Hi Gang;
Thanks for all the input Grin. I'm off today so I should have a few minutes to tinker this afternoon.

JR - I am not clear on the pins your mentioning. I'm certain it's the the ATEC plugs, which is 1 or 2, I'm not sure. I haven't seen anything on the plugs indicating pin number. Can I call you later?

I don't recall the exact error on the DDEC. I believe this was determined as normal. I can re-post this when I get back from the doc.
TTFN
-Tom
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NJT5047
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« Reply #7 on: May 08, 2009, 06:42:02 AM »

The pins for TPS are on the DDEC ECM.  I'll give you a call later. 
JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

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« Reply #8 on: May 08, 2009, 01:22:13 PM »

Thanks JR - I can call you toll free. Vonage - If that works.

I picked up a new digital Multi-Meter and have reset the TPS. I think the last number Butch and JR gave me for the DDEC I was 500 - 1500.
When it stops raining I'll hook the TPS back up and check voltages. I never concidered that before.

I disconnect the ground off the batteries for aqbout 5 minutes. One day I'll remember to mark witch switch is which :-). The code off the green light ( I think DDEC ) is 21, the Red, top light flashes 25.

The volatege between A and C are 5.3 volts at idle and full throttle.
I've looked again, my atec does not have the PINS numbered. I'll have a time checking that :-)

Trailblazer - I'm about 30 miles East of Cleveland Ohio. Thanks for askin

Voltages vary. Between a and c in 5.2 - 5.4 volts. voltage between the black and white were .5 @ idle and 4.62 WOT.

Ah Yes, Pucker power - Yep lol. I was about 60 miles from home at the time and that was my ride home. Kinda sucked.

I hope this helps and thank you all for your help!
-Tom
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« Reply #9 on: May 08, 2009, 04:01:39 PM »

Hi
I spoke with JR this evening. The voltages all check out everything acts as it should. Our conclusion on the call was it was not the TPS. Jr suggested swapping the chip set in the DDEC back to the stock set. There was no differences.
The ATEC continues to blink a 21, the DDEC a 25 I still have a Check Trans lite on the dash. :-(

-Tom
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« Reply #10 on: May 08, 2009, 06:30:40 PM »

IIRC DDEC code 25 means NO ERROR CODES

Put your meter positive lead on ATEC connector J1B pin 1P  (throttle sense)

and your meter's negative lead on ATEC connector J1B pin 2P (return)

ANY OTHER voltage OUTSIDE of approx .5volts  to 4.5 volts (WOT to Idle)   WILL CAUSE A ATEC 21 ERROR

If the voltages are within that range - than YOU HAVE A BAD ATEC


 
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« Reply #11 on: May 09, 2009, 05:26:47 AM »

Hi Peter

"Put your meter positive lead on ATEC connector J1B pin 1P  (throttle sense)
and your meter's negative lead on ATEC connector J1B pin 2P (return)"


Which set of connectors is this on the 6 wire connector or the large plugs that go into the ATEC? The plugs and wire are not marked back there. What REALLY surprised me is the plugs are not marked either.


Thank you in advance
Tom
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« Reply #12 on: May 09, 2009, 06:12:05 AM »

I sent the ATEC connector pinouts to your email addy - the file was too big to post

just look at the alignment ridges to determine which plug is which

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« Reply #13 on: May 09, 2009, 02:31:49 PM »

I tried sending you the file - sent it to the email addy you have listed in your profile

it bounced -- ask me how I feel about wasting my time and effort doing that - I tried to help - but

If you want the ATEC file with the pinout and connector discription

Then you have to send me a PM - I will only try - one more time

Pete -
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« Reply #14 on: May 10, 2009, 07:48:34 PM »

Not wasted Pete - I got it! Curious about the bounce. Would you mind forwarding the bounce to oneil.tom@gmail.com? I'd like to research it. Which email address did you send to? I don't recall if I used my Yahoo or gmail address.

The file I received will be very helpful. I'll test tomorrow before I go to work.

Thanks again!
Tom
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« Reply #15 on: May 10, 2009, 09:55:16 PM »

Hi Tom and Pete,
I would love to be included in the mailing of that PDF stuff on Allison ATEC. 
I'm at: njt5047@yahoo.com always works!
Thanks, JR

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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

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« Reply #16 on: May 12, 2009, 11:20:28 AM »

Tom,

Sorry I don't have time to pull the book out today, but I remember that after you unhook or work on the TPS there is a procedure for the ECMs to relearn the TPS. This is done by turning the power on and off about 10 times to the units, then clear the ATEC codes and you are good to go.
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« Reply #17 on: May 12, 2009, 04:46:43 PM »

Well - It looks like I may need a new (to me) DDEC. I ran the suggested tests today and am showing zero volts between P1 and P2. Now it's a little tight in there, I was a little short on time so I'll take another look tomorrow before I head into the office.
Anyone have a spare 1987 DDEC I for a NewJersey Transit they'd like to sell?

-Tom
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« Reply #18 on: May 13, 2009, 11:16:12 AM »

A last note on this...
I dug into the wiring harness deeper today. I've found 5.3 volts going to the ATEC between terminals P1 and P2 today so the DDEC appears to be good. I went back to Nimco for another ATEC. I hope to see it soon.

Thanks for your help.
-tom
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« Reply #19 on: May 13, 2009, 08:28:54 PM »

A last note on this...
I dug into the wiring harness deeper today. I've found 5.3 volts going to the ATEC between terminals P1 and P2 today so the DDEC appears to be good. I went back to Nimco for another ATEC. I hope to see it soon.

Thanks for your help.
-tom

5.3 volts is the driver voltage...would seem that the voltage would vary with the TPS position? 
Replacing the big parts is one way of resolving the problem for sure.   Hope that solves the problem.
You're on to something.  If the engine isn't showing a TPS code, but the ATEC is, that narrows down the problem considerably.   
The wiring between the ECMs is a possibility...as is the ATEC ECM. 
Since I've got the essential 'twin' to your coach (only 2 NJT numbers apart), any resolution to a failure is of interest!
JR

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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

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« Reply #20 on: May 15, 2009, 07:58:01 PM »

Well - I had really hoped this would be the last post on this topic. I'd have a solution, no check trans lite but no. Mr Murphy stopped by.
The ATEC came in today. I dropped everything to put the silly thing in and guess what! Same old thing. It did seem as though the tranny was slipping too.
I spoke with Nic at Nimco, he'll accept the ATEC back and is looking for a DDEC. He didn't seem as though he was very hopefull. So if anyone has a DDEC for a 87 NJT please drop me a line.
-Tom
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« Reply #21 on: May 15, 2009, 08:38:45 PM »

Tom,

If you only have one code and its the TPS then there is no reason to even consider buying a DDEC ECM if the engine is running OK. If you recalibrated the TPS like I told you and it does not work then you need another one based on what you have told us.

I know there is a rebuilder in Mn. that will surely beat the $600 price as well as trouble shoot your parts if needed for a reasonable cost. I next day my stuff there and its back in 3 days and repair is always cheaper than replacement.

My understanding of ATEC is that it really only needs information on throttle position to work with any engine combination.

No matter what you do to the ATEC, you must clear all codes by shifting N R N with the code sensor on before it will work again.
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$1M in $1000 bills = 8 inches high.
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« Reply #22 on: May 17, 2009, 10:30:10 AM »

Both the DDEC and ATEC use the same TPS.  The DDEC supplies the TPS signal to the ATEC.   The DDEC isn't setting a TPS code....FWIW...?   AND, the engine is running normally. 
Could the DDEC be supplying an out-of-range TPS signal, while receiving a WNR signal. 
Wiring or plug issues with the wiring between DDEC and ATEC?
Just curious.
JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

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« Reply #23 on: May 17, 2009, 12:03:48 PM »

Tom,

Tell us how it sets the code, or if the original code will not clear. If the code clears, how does it reset? Is it immediate? Do you need to push D to reset it or do you have to drive it before it resets?
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$1M in $1000 bills = 8 inches high.
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$1T in $1000 bills = 142 miles high
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« Reply #24 on: May 17, 2009, 08:14:59 PM »

Hey Gang;
I tried a few things today:
I cycled the power on/off ten times. started with a check trans / TPS
Pulled the fuses then the above.
The above the shifted NRN.
The above the NDN.
These all net a TPS error. I'll double check tomorrow on the code upon first reset.
I started thinking about what JR said about the fuse holders and checked voltages across holder all except the bottom fuse holder ( brain farting can't remember what it is ) were 12.4 volts the bottom was 11.7 - weird.
Also the voltage DID NOT vary while the throttle was pressed. - Also weird.
NJT5573 - You mentioned rebuilding parts - What do you have in mind. Nic (Nimco) didn't seem to possitive on finding another DDEC.
-Tom
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« Reply #25 on: May 17, 2009, 08:32:46 PM »

Since Tom has not answered this yet, let me try. 
When his bus is started, the 'check transmission' CEL lights up.  The bus will take off, shift thru all the gears once.   If you stop, the transmission won't shift correctly again until the engine is shut down and the system reset. 
Then it repeats the process. 
My thoughts (nothing more than a SWAG unfortunately) is that the TPS is working correctly.  The engine works just as it should.  Correct idle speed, and full throttle operation. 
Tom is working with a DDEC 1/ATEC HT748R.    There is no PWM that I can see.  Just a wired com-link between the DDEC and ATEC.   
The DDEC must be sending data beyond just a TPS signal as it is read by the DDEC unit.   If not further data, the engine wouldn 't know when various loads requiring downshifts occur.   So the TPS signal sent to the ATEC is modified by the DDEC in some fashion.   The DDEC maps have additional influence on the shift points. 
Tom had an 'upgraded' EEPROM (DDEC 1 can have HP and RPM parameters altered by changing the EEPROM).
This has been ruled out as a fault since he's replaced the new EEPROM with the old unit. 
The fault may have been induced by attaching the 12V DDEC/ATEC feed to the 24V post.   When this happened, it smoked up the battery compartment.   
The ATEC ECM has been replaced twice.
Looks like the latest ATEC Tom installed is working worse than the 'second' unit.   
It is possible that the ATEC output circuitry (drivers) in DDEC ECM is damaged.  I don't know.
On an NJT, the wiring between the DDEC and ATEC are easily accessed and to the extent of the data available, checked.   The wiring appears to be intact. 
That's what's going on.   
The DDEC 1 units are quite a bit different from the later DDEC II units.   DDEC II is a much more sopisticated system.  However, DDEC 1 units are not known for 'DDEC' failures.   They are known for having wiring issues.    Most NJTs have decent wiring.  The ATEC and DDEC ECMs are located in the rear bay so no weather or heat issues. 
Regarding the higher HP EEPROM, Butch and I are both using these EEPROMs with no problems.   They've been installed for 3 or 4 years now.   I would assume that the 24 volts has smoked something...any ideas are welcome!   
At this time, Tom's looking for another DDEC ECM to try.  That will rule the DDEC unit out.  It still could be the TPS, but if so, the DDEC ECM isn't setting a trouble code.  It flashes out '25' which is the 'normal' or the expected normal operation mode code.

JR 
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

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« Reply #26 on: May 17, 2009, 08:35:21 PM »

OOPs...There's TOM!   Wink
Tom, have you called Sam Caylor and Luke?   Luke has parted out several NJT/DDEC 1 coaches. 

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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

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« Reply #27 on: May 18, 2009, 10:50:43 AM »

Thank you for the last post JR.
One clarification. The 12 volt lead for the ATEC was connected to the ground port ( most left in the battery box ) and not 24V +.
I found this morning that by only flipping on the battery, master ignition off I have a faint light on the DDEC error code light when that switch is thrown to read the code. I spoke with JR regarding this and we feel as there is an electrical issue somewhere in the coach... code possibly be DDEC but...
Anyway been fighting migraines the past couple days, my mental capacity is... well fuzzy. I look at this again in a day or so.
I took it out to get fuel before it shoots up for the holiday. I noticed my Not Gen light flicker while getting off a ramp. Dam
-tom
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« Reply #28 on: May 25, 2009, 06:05:43 PM »

I snuck the coach out for the weekend. All freeway until the last few miles which were 35 MPH .
I had the same shift problems pulling out of town, pulled off just before getting on the freeway, restarted and the coach shifted up fine. When I made my last turn off US422 onto OH282 and accelerated the shifting was on the money. Same deal on the way home. I got off US90 onto OH44, no problems, got off at OH84 to some back streets home and it shifted on the money.
Now JR and I were talking before about the problem maybe electrical ( a short someplace ) since we found the DDEC error light would come on with the battery hot, ignition off.
Been fighting migrains the past several day so crawling in the rear bay is the last thing I've wanted to do but I'm betting it's a bad ground come place.
More later!
-tom
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« Reply #29 on: May 25, 2009, 07:57:52 PM »

Hi Tom.   Definitely an interesting problem with the DDEC CEL.
As described, pull the J1A plug and if the light goes out, it ain't a wiring problem.  If the light stays on, that would probably be good...I think.   Finding the 'feedback' or short might be an unfun job. 
It seems possible that the DDEC may have suffered an insult when the B+ was connected to ground and the ignition turned on.   Misplaced battery leads have screwed up several coaches.     
Regarding the 'No Gen' light when the coach bumps an idle...mine's done that since I've had it.  Typically when leaving an interstate or something where the batteries are fully charged.
Scared the 'P' out of me when I first noticed the light flash.   But it seems something that they do. 
I've got a marine 24V, 20 A charger hardwired to the house batteries.  When the genset is running, which I gotta do for OTR AC, the charger must be turned off or the 'No Gen' light stays on. 
Have you considerd buying a 'donor' coach?  If you plan to keep the '87 for a few more years, could be a useful item?! 
Now go take some Maxalt hits and get to work!   Wink   Keep us posted!

JR

 
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

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« Reply #30 on: June 03, 2010, 06:50:02 AM »

I want to thank everyone for their help trouble shooting this issue, the advice, diagrams have been a tremendous help. The problem is now resolved. It's been going on so long I forgot how well this coach runs. The problem was the PROM.

As you know New Jersey Transit bus's have little nuances ;-) The tweaked DDEC PROM and now apparently the ATEC PROM. Though the part numbers or the ATEC match which was the argument the parts company made they are not all the same. lol

Today I'm running a 'new' ATEC with the original PROM ( pays to be a pac rat ) the DDEC I  'HP PROM'. My god it runs well. cooler I think too!

Again thank you all four your help. A special thanks to JR, Pete and Butch and Rich at http://www.wwwilliams.com/ . You guys rock!

On to making a trailer hitch!

Again THANK YOU!!
-Tom O'Neil
Formerly NJT5049


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