1995 D12a-370 please help

Hi Guys, I am absolutely new to this...I have never "posted" anything in my life but I need help, the Volvo dealers in my area are not any help to me. Long story short, I just bought a 1995 WG64 with a D12A-370 in it from a family that I personally know. The gentleman that sold it to me got sick a few years ago and the truck has been sitting for 2 years without being started. I bought the truck and after a a long few days of not being able to get much help from local dealers because of the trucks age I have been researching online and VIOLA! This forum has more info in the last 2 hours of reading that the last week of dealer crap...

Here are the details, its a 1995 WG64, R dump truck with a VE D12A-370, serial number is 4V2JCDGF3SR833238, I replaced the 4 batteries with 4 900cca batteries, replaced the starter (the old one had a crack in the top of it and was badly rusted on the inside from water dropping down on it.

The engine cranks very fast and will run smoothly if given a constant supply of starting fluid, this done by the mobile Volvo dealer mechanic, (he said it was OK if he unplugged the intake heater).

The engine was fully primed but will not fire? The tech said that the injectors were not firing and that maybe the ECM was bad...he had no computer or diagnostic equipment or any schematics to check for power at the ECM. He did not check CAM or Crank position sensors connections (where ever they my be), nor did check or was able to explain how the fuel supply was cut off to the engine to stop it.

So I have a few basic questions, what and how does the ECM take its direction from to time the injector pulse to the TDC of the piston? How can I check power and ground to the ECM to ensure that it is active to receive communication from sensors to function properly? Does someone have wiring diagrams for this? How is the fuel supply shut off to shut down the engine?

I have had much difficulty finding info about this truck but from what I could find, it seems that the larger of the two fuel lines coming directly from the tank goes directly to the ECM and not through a "Primary" filter.

I have read many threads on this form and it has been most informative.

I have put a jumper across the low coolant sensor, with no change.

I also have the "ENGINE FLUID" light on.

I have a button the says diagnostic on it, but when I push it the check engine comes on and nothing else happens...

If someone has a wiring diagram or advice it would be most appreciated.

I am no mechanic but can read a wiring diagram, trouble shoot, and repair most anything, the challenge here is I simply cannot find information or good advice, please help!

niaymi

 

Hi baha, thanks for the response! One of the challenges that I have is that even my local Volvo dealer does not have wiring diagram for the the truck. After reading a few different threads on this forum it seems that there may be a relay that once activated then supplies power to the ECM, if that is the case where is this relay and what triggers it. The start button and its relay is straight-forward and works properly. I would assume that the ECM relay must get powered up from the key on position, that is assuming this truck even has one.

I just do not know where to start to check circuits.

Is there a electric fuel shut off solenoid like most other diesels or does the ECM simply shut off the injectors upon key off to shut down the engine?

Thx!

 

Oh i forgot to mention that I did crack the bleeder at the head and with the primer I can get fuel to squirt up about 3/8 of an inch above the bleeder. It seems like the fuel delivery system is OK. Is it possible to damage the ECM by over priming it with the hand primer?

 

Hi Pablo, thanks for the reply. I have not used any air in the tank although I must admit before I starting reading this forum the idea did occur to me. I have only used the hand primer, can the ECM be damaged with that?

I am going over to the truck this morning to check a few more things, but I do not think that the CEL comes on unless I push the diagnostic button in. I do not think the ECM is getting any power but I do not know how to check that. I do not want to damage the ECM by incorrect testing.

thx!

 

Hi Pablo, thanks for the help, the FH wiring diagram would be most helpful!

I was reading a post by you for 2012 where you were saying that on D12a's and b's that you thought that the ECM had some sort of protection module, what was its purpose, just to shut off power to the ECM to stall the engine?

Also is it possible to damage the ECM by using the hand primer?

Thank You very much for your help!

Sincerely,

Niaymi

 

Hi Pablo, my email is [email protected], Thank You very much for your help!

Just one question, is it possible to damage the ECM with the hand primer?

Thank you!

Sincerely,

Niaymi