Dead ecu

[red22dog]

Hi. 92 ranger xlt. Turns over wont fire. Fuel pump not coming on. When i use my code reader get nothing from computer. Checked fuses, inertia switch. All good. Changed 2 relays. Fuel pump and computer. Does anyone have any ideas what the cause might be? I pulled out the computer also and it looked fine. Thanks

 

[kunar]

check your grounds

 

[red22dog]

Thanks for the reply. How woud I start checking the grounds?

 

[Insanejughead]

Any place where you see a wire leading to a eyelet that is bolted to the body you will need to take it off, wire brush the hell out of it, then re-bolt it back in place.

For the computer's grounds, the pins that the grounds come from are pins: 20, 40, and 60.

Anywhere that you see a wire being bolted any part of the body or frame, take it off and check to make sure it and the bolt is clean.


From what you've told us so far, it's impossible to know if the computer is bad. Not getting any codes could be caused by the wrong wires being plugged into the test connector and/or those wires not even being hooked up to the computer.

 

[lil_Blue_Ford]

As far as grounds go, not only clean them, but get a tube of dielectric grease from an auto parts store and put some of that on the connection to help prevent further corrosion.

As far as not getting any response from the computer, check the fuse for the cigarette lighter, when that fuse pops in a lot of vehicles, you get no response plugging in a code reader.

If the fuel pump is not turning on, I'd trace that before worrying about the computer. Check the fuses and relay, check the inertia switch up under the dash on the passenger side floor (near the transmission hump). You can check for power there using a test light or meter (that will tell you if all the wiring and all is good for that part of the system), then check to see if you get power at the pump. When the key is turned to the on position (not start, but run), it will give power to the pump for a few seconds. When checking for power at various spots, you may need an assistant to cycle the key.

 

[red22dog]

Let me add this as well. I was working on the valve body, I was having an issue with overdrive. I had the wires going to the 2 solenoids disconnected. Anyway, my neighbor turned the key in the truck to the on position. I thought I saw a puff of smoke under the truck when he did that. What could have blown?

 

[Psychopete]

What could have blown?

That's like asking where the needle went that you dropped in the haystack...

 

[red22dog]

Are there any inline fuses that I can check?

 

[Psychopete]

fuses are in the power distribution block. the older models had the inline fuse links instead. but to really answer that question, you need an EVTM for your truck to reference.

Big thing that's missing is the history of this thing - did it just up and die? is this something you bought that didn't run? When was the last time it actually ran, and what happened when it died?

 

[Insanejughead]

PsychoPete, whom always asks the million dollar question and never gets paid off.