98 SR5 T100 Crank no Spark bad ECU/ECM
12-26-2016, 04:18 PM
#1
98 SR5 T100 Crank no Spark bad ECU/ECM
I picked up a non-running T100 SR5 Manual Trans 4x4 with the hopes of getting it going for a winter beater / wood huller. Anyway, I have a couple 97 4x4 T100 parts trucks to pull parts from.
Anyway, it was the last owner's daily driver till it died on his son. They took it to a shop and they diag'ed it as the ECU. I checked and the check engine light does not light up with the key on. I plugged in an auto ECU and the check engine light did light up. Cranked it and no spark. When the key is first turned on, it sparks, but nothing afterwards.
After I dollied it home, all dash lights are out, windows don't work, no crank, and I found the 3 coils all melted and cracked up (still hot). The ECU fuse is blown, and instantly blows again even with the ecu and coils disconnected.
I haven't really gotten much further, but based on the wire diagrams I've looked at, it suggests the fuse blow most likely because of the fuel pump or there is a wire pin out difference auto vs manual ecu's.
Now for my questions, does anyone know if the manual trans ecu could cause issues to the coil/no fire? I don't have another late 97/98 MT ecu and they are very expensive on ebay so I'd prefer to get it running with the AT ecu and deal with the check engine light assuming it runs/drives fine yet.
Does anyone have the correct part number for the 98 T100 ecu? The one in the truck is a reman, and the part number sticker was pulled off for some reason. I tried to look it up on a Toyota dealership site, but the part number wouldn't bring up results anywhere else.
I'm not sure if the 97 ecu I used is the early/late style (throttle body difference), but is the part numbers anywhere logged to know for sure which is which? The parts trucks I have, have been cobbled pretty bad from the last owner and his 70mph bear hunting trail riding (his wording atleast). They did break a torsion bar on one of the trucks, pretty extreme I'd say.
I'm planning to disconnect the fuel pump and replace to ECU fuse to see if it quits blowing, hopefully that's the cause. I can re-pin the ecu plugs if needed to make the auto ecu work (hopefuly), and have spare coils on another engine, so hopefully I can get it running.
Anyway, it was the last owner's daily driver till it died on his son. They took it to a shop and they diag'ed it as the ECU. I checked and the check engine light does not light up with the key on. I plugged in an auto ECU and the check engine light did light up. Cranked it and no spark. When the key is first turned on, it sparks, but nothing afterwards.
After I dollied it home, all dash lights are out, windows don't work, no crank, and I found the 3 coils all melted and cracked up (still hot). The ECU fuse is blown, and instantly blows again even with the ecu and coils disconnected.
I haven't really gotten much further, but based on the wire diagrams I've looked at, it suggests the fuse blow most likely because of the fuel pump or there is a wire pin out difference auto vs manual ecu's.
Now for my questions, does anyone know if the manual trans ecu could cause issues to the coil/no fire? I don't have another late 97/98 MT ecu and they are very expensive on ebay so I'd prefer to get it running with the AT ecu and deal with the check engine light assuming it runs/drives fine yet.
Does anyone have the correct part number for the 98 T100 ecu? The one in the truck is a reman, and the part number sticker was pulled off for some reason. I tried to look it up on a Toyota dealership site, but the part number wouldn't bring up results anywhere else.
I'm not sure if the 97 ecu I used is the early/late style (throttle body difference), but is the part numbers anywhere logged to know for sure which is which? The parts trucks I have, have been cobbled pretty bad from the last owner and his 70mph bear hunting trail riding (his wording atleast). They did break a torsion bar on one of the trucks, pretty extreme I'd say.
I'm planning to disconnect the fuel pump and replace to ECU fuse to see if it quits blowing, hopefully that's the cause. I can re-pin the ecu plugs if needed to make the auto ecu work (hopefuly), and have spare coils on another engine, so hopefully I can get it running.
12-27-2016, 01:32 PM
#2
Small update on this, I've discovered/found the TIS site for the wire diagrams etc, so I've paid for access and am downloading diagrams that I might use some day. If anyone needs anything, I'll need year, engine and model. I'll report back what I find once I study the diagrams.
02-01-2017, 07:27 AM
#3
Got side tracked with other projects a bit but back on this. I found the ECU pinout charts from the TIS site for both the 98 MT and 97 AT computers and figured out the differences. I've re-pinned the MT harness and hooked up the AT ecu and the truck will start run a couple of seconds then die like the key is turned off. Fuel pump seems to be running like normal. I double checked and ohmed the harness from ecu to mas, ecu to tps, and ecu to cam sensor (diagram suggested it could be a problem). Anyway, all have connection. A few wires did have high resistance readings but not sure if it was accurate readings or not, I was using my dad's fancy multi meter and it's all over the place even for dead shorts.
Anyway, long story short, since I have experience making wire harnesses for ATV's, I'm looking to run new wires to replace the wires that have high resistance readings. I'm looking for the part number for the terminals for the TPS and MAS. I've found the ECU female terminals already.
The OBD2 port isn't communicating, I moved pin 7 to pin 2 for the communication protocol difference, but I might have overlooked the differences in the other wires besides the signal wire.
Anyway, long story short, since I have experience making wire harnesses for ATV's, I'm looking to run new wires to replace the wires that have high resistance readings. I'm looking for the part number for the terminals for the TPS and MAS. I've found the ECU female terminals already.
The OBD2 port isn't communicating, I moved pin 7 to pin 2 for the communication protocol difference, but I might have overlooked the differences in the other wires besides the signal wire.
