Could This Have Blown My ECU?
 

Took my 95 F 350 w/ a 5.8 to the carwash to wash off the gunk in the engine compartment from the leaking power steering hoses that I recently replaced. When I was done washing it I jumped back in to go home and it almost fired then would only crank. I get no spark from the coil. Had the TFI module checked at NAPA and it was bad. Thought I had it licked then, but still no fire. Did some tests that I found to troubleshoot the ignition system and the test said that there should be 12v to three of the six wires at the TFI plug, but I only got 12v at two of them. The third wire that is supposed to have 12v is the yellow/black wire that goes to pin #4 in the ECU plug. Since this wire comes from the ECU does it mean I fried the ECU, or are there other tests that I can do to find out what might be wrong? I also tried to short a wire in the ECU plug to try to get the coil to spark and I got no spark that way either. I tried two different coils, but I am unsure the condition of the spare I had. I may have a coil problem, but the lack of 12v from the wire from the ECU has me worried.

Steve

It's possible the ECU is fried, but I'm doubting it.

Newer engines can't tolerate direct contact with water like the older ones did just because of all the electrical systems they have. You should have left the engine running while you were washing it.

So here's what I'd suggest-

First, if you think the ECU is fried, pull it out and have it tested.

Second, start cleaning any and all grounds you can find. Pull the cap and clean the contacts on the cap and rotor. Then pull the coil to cap wire, clean them and make sure they're dry. Do the same with the power wire to the coil. Then pull and clean each spark plug wire on both cap and plug end. Also pull apart any and all plugs of any kind that you can find and clean them as well.

A bottle of electronic contact/plug cleaner costs around 3-5 dollars at your local parts store and it's ideal for this type of thing.

Start there and see if you get any results. Keep us updated.

Oh yeah, and check fuses and relays as well.

Pin #4 "IDM" (Ignition Diagnostic Monitor), you should not have put 12v+ to it.

2 pins on the TFI get 12v+, one constant power key in "run", one temp power key in "start".

No start you likely have no power to ignition, test red/light green wire at coil for 12v+ with key in run and start positions.
If no power present and you want to "hot wire it", run a wire from the + battery thermal to the red/light green wire at the coil, if it starts its sure sign no power to or from the ignition.

I power wash my trucks, every car/truck we ever had/have under the hood regularly and completely, there is no place I will not spray. I let em idle and go at it to flush away road salt, never fried one yet.
Jumping wires where you're not sure what you're doing is a sure way to fry one though.

I didn't put 12v to it. The test instructions I had said that there should be 12v to that pin with the key in start, but there was not. Could you tell me which pins are supposed to have 12v and when. There is power to the positive side of the coil with the key in the run position. Didn't check in start position though. Will do that in the morning. I do get 12v to two pins in the TFI plug with the key in run position. Same in start position, too. I have always power washed all of my vehicles, also and this is the only time I have ever had a problem.

Steve

I didn't put 12v to it.

Oh sorry reading your OP kinda made it sound as if you did.

Did you figure out the problem yet?

I didn't put 12v to it.

Oh sorry reading your OP kinda made it sound as if you did.

Did you figure out the problem yet?

Looks like the site has a few issues today.

IF you get the proper voltages to the TFI, then pull the SPOUT connector out. That will alow the TFI to run at base timing, and should give you a spark without the ECU commanding it. IF still no spark, possable the pickup inside the distrubitor failed.

IF you get spark, hopefully the ECU will still fire the injectors for you. I had this happen before when the ECU did fail, it locked the TFI for no spark, but the injectors still pulsed causing a flooded engine! Removing the SPOUT connector got me home!

Haven't had time today to look at it. I appreciate all of the help so far.

DBGrif91, I have called around and no one locally can test the ECU out of the vehicle. I have a buddy at the local Ford dealer and he told me that they can't/won't test one out of the vehicle. Every plug I disconnected I cleaned before I plugged it back in. None were dirty, wet, or corroded. Checked the fuses and relays not long after i found it wouldn't start.

Eddiec1564, I have been seeing mentions of pulling the SPOUT to get it running. I think I will try that next.

Danr1, noticed the issues too. Thanks for the support.

I will keep everyone updated on what I find as soon as I get a chance to check it out. Hopefully tomorrow.

Steve

is it possible you just had water on the cap causing it to jump plug wires while trying to start it?

That was the first think I fixed. It was damp inside, but I wiped it out and sprayed it with WD40. Still nothing.

Steve

Got it running again. I think most of my problem was just a bad connection where the fusible links hook up at the starter relay. Shame on me for not thinking of that first. Anyway, I was reading through other posts on the forum and there was references to the fusible links blowing and that being a problem with the computer not getting power. Pulled the nut off of the starter relay to check continuity of the fusible links and the connections were pretty crusty. The fusible links were good btw. The spare coil I had was bad so I had to put my MSD Blaster back on and it fired right up. Glad this thing is running again. Thanks for the help.

Steve

Good to know- but I would still work on cleaning electrical connections in your off time- it's not going to hurt anything and may even prevent future issues.