Fordracer Posted September 21, 2019 Share Posted September 21, 2019 I'm working on a 2000 F-250 that lopes at idle, misses out, and has little to no power on acceleration. It has a circuit code for injector #5 (I can't remember which code it was) and a 603 and 605. I pulled back the inner fender and plugged in my spare IDM and let it hang while I started it up and it ran great so I shut it off and tucked it up in the fender so I could pull it out of my shop while the IDM is on order. When I started it back up it was running bad again so I pulled it back down while it was running and it shocked me when I grabbed it and I saw a big spark when it touched the fender. Now it doesn't run and I have codes 1668 and 1670 along with the 603 and 605. I think I fried my IDM. I plugged his IDM in and it starts and runs bad, if I unbolt it and let it hang it runs great, now it doesn't run with his IDM so I think I shorted it out also. I ohm tested and load tested the wiring from the IDM to the PCM and the injector #5 wires from the IDM to the connector on the left valve cover connector while wiggling the harness and found no problems and there are no bare wires where it rubs on the valve cover. Is it possible the #5 injector is shorting out and somehow sending voltage to the IDM housing? I pulled the valve cover and checked the UVC wiring and ohm tested the injector and all pass. I unplugged the injector and it still won't start but I think the IDM is fried now and I'm afraid to fry another IDM. Has anyone every have and IDM shock them? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted September 21, 2019 Share Posted September 21, 2019 P0603 is a KAM error but the P0605 is PCM-ROM Failure - clear all codes and re-run your self tests and if the code returns the PCM should be replaced however if it were me I would eliminate all electrical concerns before condemning either module. But the IDM shock makes me suspect an issue with the injector harness shielding which grounds through the module... which has only one ground itself. The harness shield should be pin #18 at the IDM connector and the IDM ground is pin #26 at the IDM. The PCM grounds are pins #51 #77 #103 at the PCM connector. Both the IDM and the PCM share ground G101 which should be located near the Power Distribution Box on the fender. I would load test all of the grounds from both the PCM and the IDM and inspect the harness and the ground connection. You might also want to check for injector circuits shorting to the injector harness shield as well. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted September 21, 2019 Share Posted September 21, 2019 My memory isn't as fresh on 7.3s as later engines, but I did have a similar problem on a 6.0 a few years ago. A shorted injector was backfeeding high voltage into the harness and spiking the PCM on the ground side preventing IDS communication and diag. The odd symptom was the tech had a spare EBP sensor plugged in and hanging from the harness, and it would spark when it rattled against a grounded bracket. I told him to unplug each injector one by one to determine which it was, which quickly ID'd the bad one. The failed injector had a melted magnet on it! A pump shop I know uses 2.77 -3.17 ohms acceptable resistance. IIWY I'd unplug them one at a time to see what changed...... Quote Link to comment Share on other sites More sharing options...
Fordracer Posted September 21, 2019 Author Share Posted September 21, 2019 I load tested the PCM grounds but not the IDM ground for some reason so I'll check that. I was wanting to start it with #5 injector unplugged but I don't have a working IDM now. I guess it was running bad when the IDM case is grounded but when it was not touching the truck it ran good but moving it around causing it to spark against the body must of shorted out the IDM's. The spark jumped at least a 1/4 inch gap. I guess I'll mount the new IDM in the truck and try to start it with #5 disconnected and hopefully it won't damage the new one. The 605 code is a hard fault but if it runs good after the injector issue is taken care of I'll ignore it. Quote Link to comment Share on other sites More sharing options...
Fordracer Posted October 7, 2019 Author Share Posted October 7, 2019 I think I found the problem. After putting in the new IDM I drove it a couple miles and it acted up again. I limped it back to my shop and wiggled the wiring harness on the engine and I could make it come and go. Then I grabbed #5 injector wire at the valve cover and if I pulled it out of the engine harness it would act up and if I pushed it back in it would run fine. I over laid a wire from before the connector on the left valve cover to the injector plug on the right valve cover. The customer has had it back for a work and it's still running fine. 2 Quote Link to comment Share on other sites More sharing options...
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