FICM good. But low voltage.. Any ideas???

[harlo]

I have swamps 58v FICM and my Edge Insight showed my voltage was around 40v on cold startup and would go up as truck warmed up. I checked manually with multimeter and it was low. I sent it to swamps and they said theres nothing wrong with it and to check my batteries, alt., connections and injector wire harnesses. I put it back in and when trucks up to temp it will only get to 47ish volts when it used to max the Insight out at 50v.

Anyone ever have this problem? Or any ideas? Thanks.

[harlo]

well i just put new batteries in, cleaned connections, and checked alt. and still does the same thing.

any help on thing to check would help a lot. thanks

[Lilpooh]

Not sure why, but did you check and clean all the negative battery connection to the engine block. The pass side negative cable connects to the front of the engine block by the AC compressor, it has a issue of coming loose,corrosion, or damage.

[harlo]

thanks for the reply. i just went and took it off and cleaned it. still does the same thing.

any other things to check?

[harlo]

Bump for any other things to check??

[Dave]

Its the FICM if that all tests good.

[harlo]

Well I swapped ficms with a friend and everything was good then put mine in and still low voltage. Swamps still think it's my trucks wiring but they would take another look at it if I wanted. So I sent it back to them. Im almost positive it's not my truck.

[Dave]

I know its not your rig if the other FICM is good.

[harlo]

That's what I told them. He said they tested it on the bench and put it in a truck and drove it a couple hours and it was ok. There's has to be something going on with it.

[Nu2Ford]

I have a stock FICM but it does act similarly. I've concerned about the FICM ever since purchasing the truck about 6 months ago. So I bought a Scan Gauge and began to monitor some of the critical values. What I noticed was that my FICM started low at 35v, but warmed up to 48v within 5 seconds or so. I don't have a CEL or codes and seemingly no issues, but still I'm concerned.