MY1PATH Posted February 8, 2011 Share Posted February 8, 2011 (edited) I can't win can I? Finally Got my 89 running, turns out the probelm was in the ECU. Get Federal ecu in it and down the road the same thing happens again. While waiting for my ride I open up the old CA ecu and find a burned circut on the pinted circut board. Looking at the outside of the ECU on the Far right harness, its the third pin from the right on the top row The wire is solid black with orange dots WTF I bet the the one under the seat just had the same thing happen... Maybe too much power? I think I need to check my alty. any other possible causes? I'll have to pull this other ecu out and see if it has the same issue. Then I'm gonna bridge the burnt connection and see if that gets me a working ecu (or 2) again. but WTF with the surge? and as far as codes go; 43 TPS, 12 MAF, 13 COOLANT I think they are all on the same circut... I know a bad coolant sensor will not cause any burnt wires but could a TPS or MAF do some electrical damage if it failed? Edited February 9, 2011 by MY1PATH Link to comment Share on other sites More sharing options...
RustyButTrusty Posted February 8, 2011 Share Posted February 8, 2011 Failing voltage regulator inside the alternator? What voltage is it putting out? Link to comment Share on other sites More sharing options...
crazyhayseed Posted February 8, 2011 Share Posted February 8, 2011 That's weird. If your alternator wasn't regulating voltage, I'd think you'd pop a ton of stuff before you fried the ECU... Like the headlights. In fact, I did have that problem with my 94 B13, and that's exactly what it did. Having the alternator tested would be good if you can find a shop that will give you something better than a Go/No Go test (ie: an actual Voltage measurement). Ultimately though, I think you'll need to trace you harness from the box and look for bad juju. Link to comment Share on other sites More sharing options...
unccpathfinder Posted February 8, 2011 Share Posted February 8, 2011 yea i had a bad voltage regulator and it'd get up to 17V...luckly i didn't burn out anything in my 87...but i'd def check voltage output and then start trying to figure out what it is that's burned out and track it back to a pin and try to follow it on a schematic to see what you have shorted... i found out last night that everything in the doors isn't fused...forgot to pull the 12V before clipping the wires on the old door and made some sparks...to my dismay no fuses had popped Link to comment Share on other sites More sharing options...
Simon Posted February 8, 2011 Share Posted February 8, 2011 Double check all your grounds as well. Link to comment Share on other sites More sharing options...
MY1PATH Posted February 8, 2011 Author Share Posted February 8, 2011 (edited) Ok well looking at the outside of the ECU on the Far right harness, its the third pin from the right on the top row.The wire is solid black with orange dots I have no pin out diagrams for the TBI ECU and I hate electrical stuff. Updated OP to keep info together. Edited February 9, 2011 by MY1PATH Link to comment Share on other sites More sharing options...
MY1PATH Posted February 8, 2011 Author Share Posted February 8, 2011 So I repaired both ECU's but I can't drive this thing anywhere untill I know the source of the problem. And it seems to be getting worse. I barely finished testing the second ecu when the solder melted on the repair. I took some pics too. The first one indicates the pin the circut is on. The burnt circut and the repair job are indicated by the tip of the red stir straw in the second two pics. click to enlarge... Link to comment Share on other sites More sharing options...
JamesRich Posted February 8, 2011 Share Posted February 8, 2011 Ok well looking at the outside of the ECU on the Far right harness, its the third pin from the right on the top row.The wire is solid black with orange stripe I have no pin out diagrams for the TBI ECU and I hate electrical stuff. Updated OP to keep info together. I have an 89 FSM in PDF. It's a 112 meg file though. PM me an email and I can send you a link to my dropbox so you can download it. James Link to comment Share on other sites More sharing options...
unccpathfinder Posted February 8, 2011 Share Posted February 8, 2011 Yea sadly my 87 fsm is in storage in CA so hopefully James's offer can help u Link to comment Share on other sites More sharing options...
87pathy Posted February 9, 2011 Share Posted February 9, 2011 that alty won't put out more that 18V. I ran mine for 1.5 years at 18 volts. I'd ve investigating a short. Link to comment Share on other sites More sharing options...
RedPath88 Posted February 9, 2011 Share Posted February 9, 2011 I think these may help you some It appears to be Pin 26, and it's considered to be black only, since there is no colored stripe running the length of it (same on my truck) Not sure what, if anything, the orange dots mean. But they are common throughout our trucks wiring. Link to comment Share on other sites More sharing options...
Kingman Posted February 9, 2011 Share Posted February 9, 2011 Yeah, I was talking with him about that earlier. Pin 26 is the common ground for the TPS, CHTS, and MAF sensors. Given that those are the codes being thrown, and the burned out circuit, that's where I'd start my investigation. Link to comment Share on other sites More sharing options...
MY1PATH Posted February 9, 2011 Author Share Posted February 9, 2011 (edited) I agree with there being a short somewhere. The codes are only being thrown after the burn (cutting the wire would have the same effect) so I think that almost rules out any devices malfunctioning. (unless the short is inside the device). We found a stray dog today So I did not get any time to trace wires. Bowser (as we call him) Edited February 9, 2011 by MY1PATH Link to comment Share on other sites More sharing options...
Kingman Posted February 9, 2011 Share Posted February 9, 2011 Link to comment Share on other sites More sharing options...
Kingman Posted February 9, 2011 Share Posted February 9, 2011 You know Garret, your problem got me thinking about mine. So I took apart the Z31 computer that's running my engine to see if there was something wrong, and this is what I found... Link to comment Share on other sites More sharing options...
Kyle94 Posted February 10, 2011 Share Posted February 10, 2011 BROKEN!!!! Link to comment Share on other sites More sharing options...
MY1PATH Posted February 10, 2011 Author Share Posted February 10, 2011 I think these may help you some It appears to be Pin 26, and it's considered to be black only, since there is no colored stripe running the length of it (same on my truck) Not sure what, if anything, the orange dots mean. But they are common throughout our trucks wiring. Thanks Red, thats just what I need right now. Seems the EGT is also on that circut. I hope thats the culprit since EGR was the code I hade BEFORE it failed. (I think EGT sensor is in the EGR tube to meeter its function) Still pouring over other possiblities before I brave the cold. You know Garret, your problem got me thinking about mine. So I took apart the Z31 computer that's running my engine to see if there was something wrong, and this is what I found... GOOD find JAMES! You may be up and running soon. HEY if you can get the stripe colors off a working board we could prolly fix that Link to comment Share on other sites More sharing options...
JamesRich Posted February 10, 2011 Share Posted February 10, 2011 Before plugging an ECU back in you may want to check that pin 26 with an ohm meter to ground. If it's grounded then try unplugging the EGT sensor to see if it makes a difference. The wiring under the hood is getting kind of hard and crusty with its age, you might just have a wire shorting to ground. I would think if it was a short the ECU fuse would go first though. James Link to comment Share on other sites More sharing options...
MY1PATH Posted February 10, 2011 Author Share Posted February 10, 2011 ECU fuse? Link to comment Share on other sites More sharing options...
sewebster Posted February 10, 2011 Share Posted February 10, 2011 GOOD find JAMES! You may be up and running soon. HEY if you can get the stripe colors off a working board we could prolly fix that I guess the question is whether that blown resistor is the problem, or a symptom of the problem. Link to comment Share on other sites More sharing options...
MY1PATH Posted February 11, 2011 Author Share Posted February 11, 2011 I found IT!!!time to fix it!!!wire chaffing on the radiator Link to comment Share on other sites More sharing options...
Kingman Posted February 11, 2011 Share Posted February 11, 2011 I guess the question is whether that blown resistor is the problem, or a symptom of the problem. Exactly. That's good news Garret. Too bad it took 2 computers to figure it out... Link to comment Share on other sites More sharing options...
MY1PATH Posted February 11, 2011 Author Share Posted February 11, 2011 (edited) ITS ALIVE!!! Still working on it, I think being floolded out of its mind with raw fuel thinned out the oil... I got a filckering oil light.(stays off above 1100RPM) No signs of damage yet but I'm sure its life is diminshed some. It probably needs new plugs after this too. Off to change the oil... 1100PM So Oil came out thick as water and smelling like fuel. It seemed like too much came out. I might be able to run a 2-stroke off this @!*%. I poured some ATF thru it and that also came out with a mild scent of fuel. I Put fresh oil in and truned it over. No more oil light the dipsick has a very mild scent of fuel(or that may be my hand) and I am prolly gonna do the oil again on payday just to be sure. Edited February 11, 2011 by MY1PATH Link to comment Share on other sites More sharing options...
MY1PATH Posted February 11, 2011 Author Share Posted February 11, 2011 (edited) so While I was running diagnostics under the hood a cloud of smoke suddenly errupted from under battery. I kill power and unplug yet another smoking ECU and invesigate under the battery. I Pulled the entire wire harness off the engine to look at it better. And what I saw was some chafing where my Fan bracket is. Opening up the bundle I found 5 damages wires. some were so bad the copper itself had melted. a few ajacent wires also had their jackets fused togehter from the heat. I cut the wires and stripped them back some. The black wire needed a new jacket made of shrink tube. for 2 of the smaller wires I twisted in some more wire at the tip for greater contact inside the crimp. everyting got taped back up and then I taped a hose over that for extra padding. Later on I will shave down my fan brakcet by .75" so the bundle has more wiggle room. (I forgot to take a pic of that) And lastly all my work was supervised by my trusty friend who just sat and did nothing. Edited February 11, 2011 by MY1PATH Link to comment Share on other sites More sharing options...
JamesRich Posted February 11, 2011 Share Posted February 11, 2011 ECU fuse? There is a fuse for the ECCS system I think it's labeled as engine control. Good job on finding the problem, with all those wires open you might have had another power source sending power into the ECU on that pin which would explain why it didn't burn a fuse. James Link to comment Share on other sites More sharing options...
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