1994 CH613 E7-400 no start

[Glen Gonyea]

I have a 1993 CH613 E7-400 no start..Used to run fine but is shut down and has not started on its own.It looked at first the issue was at the harness plug from the back of the injection pump...We removed and soldered the wiring but still have a issue..OK but I can get it to start by adding a quick ground to pins 1 or 2 at the ecm(output to the fuel actuator)..beceause when I remove the shutdown relay put the powerprobe at pin 87 i have a ground feed from ecm through fuel actuator but when i turn the key on it drops out..grounds have been cleaned and checked on the truck..

Also when its running the RPM gage does not work either, same there if during cranking I add a quick ground to pin M4 on the gage cluster it starts and runs...1. it almost like a ground in the ECM is bad 2. but if the ECM was bad would it run at all? 3. when it does run there is no tach (looks like the ECM processes the tach signal)

Questions

1. does any one have a in depth wiring diagram of the bosch ECM for this? I have the basic VMAC diagram

2. If I replace the ECM would a ECM from any 1994 E7-400 work? Does the dealer need to program a used ECM

3. or is there a oil sensor signal needed to give this ecm a ground to start up?

4. Am I missing some stupid here

Edited November 4, 2015 by pinkeejim

[Challenger]

Plugging a known good (test) module in would be the best way to go. Can you take one out of another truck? Maybe if you have a cool Mack dealer they would let you borrow a test module, usually a mechanic will have one. The dealer I worked at wouldve lent one out.

[Glen Gonyea]

Yup I never get the easy one...I'm going to call around and see if I can find a test module...its good info, thanks...any input on this will help out..This could be a costly repair I have to get this right....Is there a website that has wiring and troubleshooting diagrams of sorts for macks..at a good price of course..

[Jeremy_Brault]

Wiggle the wiring harness around back of engine, by air compressor. They break their.

[Challenger]

Answers to your questions-

1--They only diagrams Ive seen are the VMAC diagrams. Im not sure about more in depth ones.

2--You can plug in any VMAC I module and or Bosch module and run your truck. It wont have the correct serial numbers but it will run. I do not believe you will notice any difference. If you buy a new module it will need programmed at the dealer. Some owners are ok with things not 100% some arent.

3--If the oil pressure sensor or coolant temp sensor is unplugged the truck should still start. The shutdown light would come on but the truck will start.

4--Not sure. I would check the harness like Jeremy_Brault said.

You seem like you know what you are doing. Ive always had access to test modules, so its part of my troubleshooting.