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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
Satisfied Customers: 44430
Experience:  16 years experience
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Where is the ECM located on a 1994 Ford Ranger

Customer Question

I can''t get my 1994 Ford Ranger XLT to start. It was running fine but then began to break up at excelleration. I replaced the 2 O2 sensors, Mass Air Flow Sensor, Throttle Position Sensor. It continued to run rough and gradually got worse. Then it began to sometimes run and sometimes not even start. Now it is dead. I can turn it over and spray starting fluid into the air flow intake and the engine will run as long as I keep spraying so there is spark. I noticed I could no longer hear the electric fuel pump come on when I turned on the ignition. I removed the bed and put a meter on the fuel pump and only have 5 volts when the ignition is on and the pump will not run. I located the emergency fuel shut off switch and tested it and it tests ok. I ran a wire directly to the fuel pump from the battery and the pump comes on and fuel circulates throughout the system. But when I try and start the car, it still will not start unless I spray starting fluid into the air intake. I think the ECMs bad
Submitted: 8 years ago.
Category: Ford
Expert:  Chris (aka- Moose) replied 8 years ago.

Here is the ECM/PCM location.

 

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Customer: replied 8 years ago.
What is your troubleshooting opinon based on what I have tried so far? Does these symptoms indicate a breakdown and then failure of the ECM?
Expert:  Chris (aka- Moose) replied 8 years ago.

I would start by looking into the fuel relay since the fuse sends the 12 volts to the fuel pump when the relay is commanded. you may have a command concern to the relay or a bad relay.

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Customer: replied 8 years ago.
I already tried swapping relays and even put a volt meter on the output of the relay and the relay is clicking and sending 12vdc when the ignition is on. However, even when I manually send power to the fuel pump and get the fuel to the injectors, the engine will not fire unless I spray starting fluid into the air intake.
Expert:  Chris (aka- Moose) replied 8 years ago.
What fuel pressure are you getting at the injectors. Since you just stated the fuel pump is getting 12 volts so it is running.
Customer: replied 8 years ago.
I am not sure, although when I disconnect the steel braided fuel hose connector in the engine compartment that connects the injectors to the fuel line, and then manually put 12vdc tot he pump, fuel shoots into the air.
Expert:  Chris (aka- Moose) replied 8 years ago.
Have you checked injector signal pulse.
Customer: replied 8 years ago.
No I have not done that. I just concluded there probably is no signal since I know there is spark and fuel is not getting to the cylindars, and even when I force the pump to pump fuel, it still does not fire, hence my conclusion the ecm is bad based on the decline in engine performance then total failure. What should the pulse read?
Expert:  Chris (aka- Moose) replied 8 years ago.
You can check the pulse with a 12 volt light bulb connected to any of the injector connectors. One wire is hot from the PCM relay and the other wire is signal ground pulse from the PCM. The PCM knows when to pop the injectors via cam sensor.
Customer: replied 8 years ago.
If no pulse, what would be your conclusion? Is that pulse generated by the ECM? and is the fuel pump controled by the ECM? being that there seems to be 2 problems maybe related or maybe coincidental.
Expert:  Chris (aka- Moose) replied 8 years ago.
If you have outgoing 12 volts from the fuel pump relay then you have a fuel concern between the relay and the pump and the inertia switch is in the middle there. The PCM tells the relay to turn on. The PCM does generate the injector pulse but it maust get cam position signal to know when to fire.
Customer: replied 8 years ago.
OK, Thank you for your time and assistance. I will check the pulse, inertia switch and the cam position signal. I will check back with you after that. Thanks for all your help and I look forward to your assistance in the future. Great service.
Expert:  Chris (aka- Moose) replied 8 years ago.
Your welcome
Customer: replied 8 years ago.
Chris, I just noticed I had the year wrong. It is a 1992 Ford Ranger, not a 1994. Does the above locations and diagrams still apply?
Customer: replied 8 years ago.
IF not can you update the wireing and location for me?
Expert:  Chris (aka- Moose) replied 8 years ago.
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