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Author Topic: Low oil pressure shutdown ?  (Read 5104 times)
Sojourner
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« Reply #15 on: February 18, 2009, 08:24:04 PM »

Amen to Ace's post! Very good point to remove its trouble code and retry. I doubt that may be the problem

Before Ace posted his latest, I was getting this ready to post this for fwiw supports.

From what all you have done via replace sensor and override with air pressure…still at 15 psi with engine not running or at all speed is lightly to be ECM unit. Take the ECM unit or bus to a service center nearest you.

DDEC codes

Detroit Diesel Service Location

Detroit Diesel Customer Support Network (DDCSN) for series 60/50 and newer engines.

FWIW

Sojourn for Christ, Gerald
« Last Edit: February 18, 2009, 08:27:41 PM by Sojourner » Logged

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« Reply #16 on: February 19, 2009, 04:11:24 PM »

Ace,

I have been using "sending unit" and "sensor" interchangeably, because they are both electrical variable resistors - as I understand.  That may be incorrect and misleading. 

Anyway, the two are different.  Thus, if you change the one, it will not fix the other.

I know we are trying to correct a 6V92.  However, on my Series 60 coach, the ECM sensor is far forward, and on the right side of the coach.  It is very hard to access, and takes about a 1 1/4" deep socket to remove.

Discussion on another board have suggested that 3 sensors be kept in the bus because of the likely-hood of a future failure - TPS (throttle position sensor), oil pressure sensor, and turbo boost sensor.  I have had 2 of the 3 fail.  I have good INTENTIONS to carry a turbo boost sensor.

Ed Roelle
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« Reply #17 on: February 19, 2009, 06:54:06 PM »

Ed, you may be right but it was my understanding that a sending unit is doing just that, sending the required voltage to a particular electrical gauge , where as a sensor senses a problem from within the circuit that is wired to and in turn sends a signal to the ECM, not a gauge, and the ECM is told to shut down the engine to spare the owner from costly repairs or not!
I know I may be all wrong on this but this is the elementary way it was described to me!

As for the 6v92? It should be just like my 8v92 as far as oil pressure sensor placements!

Looking at the front of the motor which is the back of the bus, the OP sensor should be on the lower right about mid way up from the bottom. It should have a single wire going to it.

Ace
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NJT5047
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« Reply #18 on: February 19, 2009, 07:30:36 PM »

That single wire sender that Ace references is not the DDEC oil pressure sensor.  That is the dash guage sender.
What about fuel in the oil pan?  SWAG  That's the only new thing I can think of beyond what has been discussed.. 
However...the DDEC system doesn't read off the dash oil pressure gauge.   It has its own separate oil pressure sensor and reference port.  Ed, Sammy and Pete have described the sensor but the description is getting lost (IMHO).
No matter what the dash says, that reading is irrelevent to the DDEC system. 
If I read correctly, the DDEC oil pressure sensor has been replaced (3 wire sensor)?   If so, remove it, and attach a mechanical oil pressure guage to the DDEC oil pressure sensor port...not at the dash guage port, and see what the oil pressure is at that point in the block.  The engine won't run long without the input from the sensor.  But, the oil pressure may be different from the engine room or dash guage.  This could be bad.  Very bad.  And as someone said, you could pressurize the DDEC sensor with regulated air pressure to verify (rule out) everything downstream from the oil pressure port.  I would want to verify that the DDEC port has good oil pressure.  The DDEC  can be sorted out.   I apologize if I missed this step and it has been done...?
Until the DDEC sensor (not guage sender) oil pressure is verified, who knows?   Once oil pressure is verified at the DDEC port, then all the other components that make up the DDEC system become suspect.   If the DDEC oil pressure sensor has been replaced (not the dash 'sender'), and the wiring is proven, the DDEC ECM is left.  If there's a wiring problem, it's between the DDEC oil pressure sender and the DDEC ECM.  All in the rear of the bus.   
Or, as the DDEC manual sez, "you have failed to correctly indentify the failure"...repeat the diagnostics.
If followed correctly, a DDEC manual will sort out the code 45 problem.   
If the engine has an oil pressure guage plugging the DDEC OP sensor, and about 40 lbs of air pressure is placed on the
DDEC OP sensor, it should run without setting a code 45.  Even if the engine has zero oil pressure.   So, if the pressurized DDEC sensor sets a code....you got a bad sensor, bad wiring or plug, or a bad ECM.   The pressurized oil sensor will rule out the DDEC quickly.   The engine must be running to verify that the code is set when the unit is pressurized.  You may want to emulate the pressure as the engine is started.  The DDEC ECM may show an 'out of range' if the pressure is too high or low for a given RPM.  Around 30 to 40 lbs should be WNL.
Good luck, JR

 
« Last Edit: February 19, 2009, 07:53:11 PM by NJT5047 » Logged

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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Blacksheep
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« Reply #19 on: February 19, 2009, 07:56:12 PM »

JR you are correct! I was cornfused! I changed so many sensors and senders on mine I got them mixed up and without looking at them this late in the night, well you know!

Ace
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luvrbus
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« Reply #20 on: February 19, 2009, 07:58:54 PM »

The DDEC compares the oil pressure to the RPMs and for what ever reason the sensor and the ECM are not in communication with each other, he has to good of oil pressure according to the manual gauge  

good luck
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« Reply #21 on: February 19, 2009, 08:13:06 PM »



The DDEC compares the oil pressure to the RPMs and for what ever reason the sensor and the ECM are not in communication with each other, he has to good of oil pressure according to the manual gauge  

good luck

Not in communication, or not in sync?   If OP is too high, that's an indication of a problem (out of range).  The only reason the DDEC and the sensor were not in comm with each other is failed wiring.   The ECM constantly samples the OP sensor.   The first question is what IS the oil pressure.   I agree that the OP varies and is sampled by the ECM.  However, there is  range within which it works.  It is not an extremely narrow test. 
The manual and dash oil pressure may or may not be the same at the DDEC OP sensor port. 


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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.”

Ayn Rand
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« Reply #22 on: February 19, 2009, 08:34:58 PM »

JR, any oil port on a 92 series is going to be about the same pressure, the ones at the front are around 2 lbs higher than the back of the engine.Let him put the sensor into another port it doesn't care where is located as long as it is in one of the galleys.    Good luck
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Sojourner
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« Reply #23 on: February 19, 2009, 09:49:54 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.

Please....read bpo first post and take notes of the underlines. I believe RTS/Daytona (Pete) has the correct answer....
Quote
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.

bpo...do you have DDEC and/or engine manual or just the ProLink manual only? You may looking at the wrong sensor?
FWIW

Sojourn for Christ, Gerald
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Ps 28 Blessed be the LORD, because he hath heard the voice of my supplications. The LORD is my strength and my shield; my heart trusted in him, and I am helped: therefore my heart greatly rejoiceth; and with my song will I praise him
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