I have an old Model A Ford a customer brought me a few months back that I've been working on off and on as I get time for it. We are cleaning up some of the wiring and aesthetics of the engine including moving all the computers (including the FICM) inside the car behind the dash. Last night we got it to the point we could start it. It was building rail pressure and the injectors were trying to fire, but it just wouldn't run. I'm wondering if anyone who has relocated the FICM has any guidance they could help with. I used 14 ga wire and ended up adding probably 5' or so to the harness. We also removed a bunch of unneeded wires and pared the wires down to enough to run everything through the small bale connector, including the injector wires coming from the FICM. I'm wondering if the wire I used is too small for the length I ran or if maybe running them through the bale connector has added too much resistance to the circuit keeping them from firing correctly. I would appreciate any assistance from guys who have relocated their FICM. Thanks guys.
Moving computers inside the cab
- Thread starter JoshH
- Start date
I'd check if you haven't already to make sure a pin didn't unseat and gets pushed back when you plug the connector in. Also that your pinout is correct and you're not off a wire.
5' I would think would be fine as long as your connections are all tip top.
Check the dumb shit too like fuses and whatnot.
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5' I would think would be fine as long as your connections are all tip top.
Check the dumb shit too like fuses and whatnot.
Sent from my D5803 using Tapatalk
Josh I probably added 4' to mine and haven't ever had an issue. You're problem is probably somewhere else.
Couldnt be a vats prob could it?Any codes?When i put mine in the stack i had a starting issue that ended up being the cps,swaped that and fired no prob.
I was thinking VATS too.. But if it won't fire and die, I'm not too sure.. Unless there's that much air in the lines maybe?
Sounds like it could be a rail pressure problem if you've already verified the injectors are trying to fire.
When we first tried to get my truck running after my harness tricks, Ben found that the Engine speed signal pin was loose in the connector. I had the same symptoms as you have now.
I'm assuming you have extended the wires that go to the crank, and cam position sensor, as well as the rail pressure sensor?
If so did you use "shielded" wire? Those 3 circuits should use shielded wire. Otherwise you could be getting some interference maybe?
I extended all of the wiring on my pulling truck back in 2010 and I haven't had any issues with it since. But I did use shielded wire for those sensors.
If so did you use "shielded" wire? Those 3 circuits should use shielded wire. Otherwise you could be getting some interference maybe?
I extended all of the wiring on my pulling truck back in 2010 and I haven't had any issues with it since. But I did use shielded wire for those sensors.
As long as you splice after the shielding you'd be all set to use normal wire without anymore shielding. It's a tight squeeze to strip and solder and protect the integrity of the factory splice, but I have done it.
Are you talking about the engine speed signal wire between the ECM and FICM?
It was so long ago since I built that part of the harness, I can't remember if I had to extend the cam/crank speed sensor wires or not, but if I did, I didn't use shielded wires. I do know I was getting a speed signal, the scan tool was showing engine rpm.
That doesnt mean anything.
The CKP and CMP sensors are wired directly to the ECM, not the FICM.
The ECM then processes and filters the raw signal from the CKP sensor, reformats it into something that the FICM can use, and then outputs it to the FICM via a discrete "replicated engine RPM" signal wire. Kinda like how the TCM reads the raw output speed sensor signal, and then reformats it into a traditional square wave replicated TOSS signal for the ECM and ABS and cluster.
If that wire has a bad connection, the ECM will obviously know engine RPM and report RPM on a scan tool, but the FICM wont know RPM.
Right, I understand that. I remembered moving the engine speed signal wire that goes from the ECM to the FICM. Is that the wire Tim was talking about that you helped him figure out was causing his problem?
Yeah I think so....it was a couple years ago.
Have you put a scope on that wire to check that its outputting a nice clean square wave?