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Author Topic: Low oil pressure shutdown ?  (Read 4957 times)
bpo
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« on: February 16, 2009, 02:59:50 PM »

I have a 6v92 with a ddec II. I am getting a code of low oil pressure with a MID of 128. I have changed oil pressue sensor and put a manual gage in place of the sensor and it shows 30psi @ idle and 65@ 1500rpm. with my pro-link hooked up it shows 15 to 16 psi on the pro-link no matter what rpm you use. Today I took the sensor off and hooked it to air pressure of 65psi and the pro-link still only showed 15 to 16 psi.

Any suggestions !

Thanks.
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Sammy
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« Reply #1 on: February 16, 2009, 03:14:50 PM »

What code is it, a 45?
Is it a Code 35 or 36?
I can help you if I know the exact error code it logged.
Are you sure the mechanical guage is accurate?
For a Code 45 it says to go to engine service manual, but it seems like you definitely have oil pressure.
I can provide wire and pin numbers for you to check the harness first, then if all checks out properly you can replace the sensor. Let us know. 
« Last Edit: February 16, 2009, 03:23:36 PM by Sammy » Logged
bpo
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« Reply #2 on: February 16, 2009, 03:44:33 PM »

Sammy, I forgot to mention that I also tested the wire harness and it checked out just fine. I am no expert with my pro-link, all I see is it shows low oil pressure but I do not see a code #.
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Sammy
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« Reply #3 on: February 16, 2009, 04:48:12 PM »

Hook up your ProLink and look at top left or right for flash code.
Glad to hear you have already tested your harness and it's good.
Oil pressure is good with a mechanical guage.
Only one thing left to do now: replace the sensor.
Good luck with your repair.
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RTS/Daytona
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« Reply #4 on: February 16, 2009, 05:19:01 PM »

Sammy - he already replaced the sensor

BPO - the oil pressure sensor wiring
pin A --> circuit #452 pin Y-2  (sensor ground - serves multiple sensorrs)
pin B --> circuit #530 pin P-2   (some voltage between .5v to 4.5 volts that corresponds to oil pressure
pin C --> circuit #416 pin W-1 (sensor +5 volt - serves multiple sensors)

check that +5V line and Sensor ground line is "AT THE" Oil pressure sender (OPS)

Check the voltage at pin B sensor output (put your + lead on pin B and the minus lead on pin A)  - does it vary from IDLE to fast idle
if it does - but the pro-link stays the same 16lbs - then it's the DDEC  (a DDEC failure would be very very rare)

Many of the other DDEC 3 wire sensors are about 2500 ohms - check what your OPS is from pin A to pin C

then try to pressurize the sensor angain and put your meter on pin A and pin B and see if it changes with the pressure

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Blacksheep
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« Reply #5 on: February 16, 2009, 07:05:29 PM »

Hey Guys I talked to him last night and he told me (if I understood him correctly) that his bus would run all day long at fast idle without any issues of shut down. It wouldn't shut down until it was at low idle after it warmed up! It has good pressure at high idle which would not allow it to shut down.

Today I asked the mechanic working on my bus about it and he thought it was just a low pressure mechanical problem. He thought that when the oil warmed up, it thinned out enough to cause a low pressure which at that time would cause the sensor to send the shut down signal to the ddec.

My first guess was the correct wt oil because that is what I found with mine when I bought it!

Sensors have been known to be bad when purchased as well as gauges so that's another guess!

There's also oil pressure regulators in the crankcase that could be faulty but that is over my head!

Other than what I already advised which was first to check all the harness connections for "green" oxidation, the correct wt. oil, grounds, harness connections, etc., going back to the pro-link saying there is low pressure, it almost has to be mechanical.

Ace



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RTS/Daytona
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Pete RTS/Daytona ->'89 TMC 35' 102" 6V92TA 4:10


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« Reply #6 on: February 16, 2009, 07:42:29 PM »

ACE

BPO's original post stated -->... I have changed oil pressue sensor and put a manual gage in place of the sensor and it shows 30psi @ idle and 65@ 1500rpm. with my pro-link hooked up it shows 15 to 16 psi on the pro-link no matter what rpm you use...

Pete RTS/Daytona
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Blacksheep
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« Reply #7 on: February 16, 2009, 07:47:44 PM »

Pete unless I misunderstood him he told me he "t'd" off from the sensor with a gauge and that he had good pressure but this was only at high idle for a long period of running time. It would only shut down after he went to regular idle which to me tells me the pressure dropped below what the sensor will allow. Could be too thin of oil!

Ace
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bpo
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« Reply #8 on: February 17, 2009, 01:43:54 PM »

Ace, I know we talked about alot of things in a short time and I may of gave you incorrect information, actual I can run it @ idle all day long without throwing a code, its when you go to 800 rpm or more is when a code comes up.

BPO
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Brian Diehl
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« Reply #9 on: February 17, 2009, 02:46:05 PM »

I would throw out the option of just putting another new sensor on.  It would not be the first time a bad sensor made it all the way to the customer.  Is a new sensor so expensive that this is not an option?
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NJT 5573
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« Reply #10 on: February 17, 2009, 07:20:25 PM »

With DDEC 2 you can unplug the sensor and rule it out. If its unplugged, DDEC just does not read or react to that parameter.

Mine will shut down if its just a couple of quarts low on oil, its real touchy, even when it is barely low, it will shut down if its that time of month! Humor it and put 1/2 gallon of oil in it and see if it likes it. Is it parked nose up hill? Mine runs a code everytime it gets on an uphill pull and is even slightly low on oil.

What is this engine in? Does it have dash diagnostic ability like an Eagle or RTS?
« Last Edit: February 17, 2009, 07:31:53 PM by NJT 5573 » Logged

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« Reply #11 on: February 18, 2009, 10:16:47 AM »

On my Series 60,  DDEC III as I remember, there is an oil pressure sensor for the dash gauge, a mechanical gauge in the rear, and a separate oil pressure sending unit for the ECM.  Mine failed this summer.

Please do not take this as insulting.  Since the sending unit is suspect, are you sure you have changed the ECM sending unit - assuming 6V92 is similar?

Ed Roelle
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Blacksheep
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« Reply #12 on: February 18, 2009, 02:05:56 PM »

Ed not to dispute what your saying but correct5 me if I'm wrong.

Wouldn't the dash gauge only require a sending unit since it's an electrical gauge and not a sensor, and wouldn't the ECM require the pressure sensor? The gauge on the rear is mechanical I believe and requires nothing as it's tapped directly into the oil line system. Again, I think!

Ace
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bpo
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« Reply #13 on: February 18, 2009, 06:01:36 PM »

My bus is a 1988 mci102a and I am receiving a code # 45

Thanks.
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Blacksheep
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« Reply #14 on: February 18, 2009, 07:12:18 PM »

Brian, I got this off the internet. I can retrieve what my diagnostic book say tomorrow as it is in the bus which is still in the shop.

<Codes 43, 44, and 45 are critical codes and if they are shown, the Stop Engine Light will come on which causes the engine protections to engage and your engine may shut down. All other codes will cause the Check Engine Light to come on which will not engage the engine protections and will allow the engine to continue running. If any of these codes are shown, please contact the nearest Detroit Diesel service center at (800) 924-4265.>

If you have a pro-link, you can see if this is a recent code or a historic code. If it is a historic code, you CAN go in and erase it, and any other historic codes that may be stored in the ECM.

I would suggest doing that (erasing all old codes) and then start from scratch to see if you have ANY NEW codes.

If you checked the harness, and you erase the codes, then have no new ones, there is no reason to have a shut down. If you have NEW codes after you erase the OLD codes, then that will tell you and us more.

You said that you can let the engine idle for a long while but then after that period it will shut down, it could be a bad connection as I said in one of earlier conversations. Bad connections and vibrations can cause you a lot of havoc. I know! Check to see if the connectors are good and clean at the ECM. Make sure there is NO green around the pins on the harness or the female side on the ECM. Also make sure you have the proper voltage going to the ECM. Low voltage will also play games with the ECM causing codes that you really don't have. I once checked mine with low voltage and came away with 7 different codes.

As I said, if you have a bus with electronics (DDEC)  like this, do yourself a HUGE favor and invest into a pro-link! Also look for a DDEC diagnostic manual. I got mine from Ebay! It can be one of your best sources of information not to mention educational.

Ace
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