So i got a "new" ECU, well its used but its in great condition. Tested The IGSW to E1 on the new one and it had good resistance, the old one had something like .4 ohms. But before it hooked it up i wanted to check the power to make sure that i don't somehow fry this one too. so i did what the Repair guide said, except i didn't hook the connectors up to the ECU like it recommended in the book. Would this cause it to give me a miss read?
Can't get any diagnostic codes
- Thread starter KMinAF
- Start date
Yep, .4 ohms is not going to fly. No wonder it was blowing the fuse.
In this case it doesn't matter if the ECU is plugged in when checking the harness. Test IGSW referenced to E1 on the connector. Should see battery voltage with the key on. If you do, plug the new box in and fire it up. If it's working right the MIL will come on. As to why it failed stuff happens. Since the EFI fuse protects most of the ECU don't worry about it.
I'll spare you the technical reasoning behind it but the old one should be easily repairable...
In this case it doesn't matter if the ECU is plugged in when checking the harness. Test IGSW referenced to E1 on the connector. Should see battery voltage with the key on. If you do, plug the new box in and fire it up. If it's working right the MIL will come on. As to why it failed stuff happens. Since the EFI fuse protects most of the ECU don't worry about it.
I'll spare you the technical reasoning behind it but the old one should be easily repairable...
Thanks!! I swapped out the computers and it worked like a champ. Now I just have to check the diagnostic codes. By the way where would I find the "how to" on that old computer? Is there some kind of website I could visit?
You're welcome. Glad you got it resolved. Proves a schematic, meter, and the Ohm's law thing beats floundering around.
There's no site that I'm aware of and although I haven't been inside the box for years in theory there can't be much to the front end circuitry for that function. It should therefore be repairable by anyone with basic electronic skills. Perhaps 3p will chime in to confirm as he's currently familiar with the hardware.
There's no site that I'm aware of and although I haven't been inside the box for years in theory there can't be much to the front end circuitry for that function. It should therefore be repairable by anyone with basic electronic skills. Perhaps 3p will chime in to confirm as he's currently familiar with the hardware.
The most likely culprit is a protection diode that is shorted (D105 on a 7MGE board), but may be some other designation on other models. Its the first diode to ground if you trace the IGSW circuit. Other components could also cause trouble, like the MREL protection diode, but you will have to troubleshoot it yourself.