Bad IRCM???

[jlunde15]

Hey all, I think my IRCM has bitten the dust. I have no power to anything, ever. Battery is fine, and if I apply 12v power, via power probe, to the under hood fuse box, I have lights, radio, clock, locks, windows, etc. for all of about 2 secs till power probe circuit breaker trips.

I also found out that if I apply power to separate pins of IRCM, I can get the individual items to power up, ex. can prime fuel pump, kick on radiator fans. Does this sound like a bad IRCM to y'all?

Because of this, I'm looking for an IRCM box with an "M" designation and was wondering if anyone had one they would be willing to part with.

 

[deercrusher]

Sounds like it to me....

 

[pjtoledo]

What year? other possibilities are power to the ICRM, and especially for the rust belt guys, the splices in the power circuit tend to corrode. I once pulled a wire out of one and found green powder where the copper used to be. Shouldn't be an issue in Tx though.

 

[jlunde15]

What year? other possibilities are power to the ICRM, and especially for the rust belt guys, the splices in the power circuit tend to corrode. I once pulled a wire out of one and found green powder where the copper used to be. Shouldn't be an issue in Tx though.

its a 92 bone stock motor. as far as i can tell, wires aren't a problem as of right now. it's a TX bred bull, so rust shouldn't be an issue just yet

 

[projectSHO89]

No, you do NOT have an IRCM problem. The IRCM does not have anything to do with any power EXCEPT for the PCM, the fuel pump, the AC clutch, and the electric fan.

You need to investigate the red wire from the battery positive terminal to the fusebox. IIRC, on the 92, the big cable goes to the starter relay on the driver's fender. There are then several other wires hanging off that same stud that have fuse links inline. One of those might be blow or the wires may be on the wrong terminal. There's another fuse link hanging right off the battery on early SHOs, but I don't remember if it was still there in 92 MY.

I'll see if I can get my 92 wiring diagrams back online later. In the meantime, be careful who you take advice from.... Most mean well, they just don't have the accurate technical details either in hand or head.

 

[lowc]

No, you do NOT have an IRCM problem. The IRCM does not have anything to do with any power EXCEPT for the PCM, the fuel pump, the AC clutch, and the electric fan.

You need to investigate the red wire from the battery positive terminal to the fusebox. IIRC, on the 92, the big cable goes to the starter relay on the driver's fender. There are then several other wires hanging off that same stud that have fuse links inline. One of those might be blow or the wires may be on the wrong terminal. There's another fuse link hanging right off the battery on early SHOs, but I don't remember if it was still there in 92 MY.

I'll see if I can get my 92 wiring diagrams back online later. In the meantime, be careful who you take advice from.... Most mean well, they just don't have the accurate technical details either in hand or head.

^^^this i had similare issue with my 92 and it was in the power wire to the fuse box

 

[projectSHO89]

I once put the rat's nest of wires on the wrong starter relay stud on my 89. Took me a few minutes to figure it out ...

Okay, bear in mind that it's been AGES since I've been under the hood of a 92 so I'm working off the factory EVTM here... Someone who is current on the 92, please step in and either correct or confirm the following:

Looks like the fender-mounted starter relay is gone (my 89 was like that). As near as I can tell from the schematic, the red battery cable goes to the starter itself, and the feed cable for the rest of the vehicle is piggy-backed on the same stud. That cable goes *somewhere* so that it feeds the engine compartment fusebox and the alternator (via fuse link). That's as much detail as I can come with without a 92 in front of me. Hope some else who has one can jump in with specifics.

 

[lowc]

ok you are right the main power wire comes off the battery and goes to the starter. then two wires come off the same post on the starter,and one goes to the alt and the other goes to the fuse panel between the firewall and strut tower. the wire that goes to the fuse panel also has a ground wire and a few fusable links on it

check the wire going from the fuse panel to the starter it runs above the trany then across the sf its probly split or rotted if its poping your power probe

 

[pjtoledo]

Ok, I've a 92 EVTM in front of me.

under power distribution the red + starts at the battery (of course) and goes to the starter, then on to the common side of the engine compartment fuse panel. According to the book, no fuse linksbetween the battery and fuse panel. Fuse links are on a branch that goes to the alternator, don't worry about them yet. So the engine compartment fuse panel should be hot at all times. The red wire may go directly from the battery to the fuse panel, wiring diagrams can be a bit mis-leading at times. end result is still the fuse panel should be hot at all times. one of those fuses is the EEC Relay fuse, 30A, and power leaves it via a yellow wire (circuit 37), goes to a splice, then two wires continue on thru connectors to the IRCM pin 8 and EEC pin 1. both of those should be hot at all times, if the EEC relay fuse is good.
other fuses send power to the ignition switch and the instrument panel fuse box.
you stated things started working when power was applied via tester to the engine compartment fuse panel? that would indicate no power there. check connections at the battery, starter, and engine fuse panel. if that does n't work start following the wires physically.

damn, now I have a headache.


Perry

 

[pjtoledo]

ok you are right the main power wire comes off the battery and goes to the starter. then two wires come off the same post on the starter,and one goes to the alt and the other goes to the fuse panel between the firewall and strut tower.

the wire that goes to the fuse panel also has a ground wire and a few fusable links on it
are you sure a power wire has a ground? it's dark, cold, and I'm too lazy to go out and look right now.



check the wire going from the fuse panel to the starter it runs above the trany then across the sf its probly split or rotted if its poping your power probe

Perry

 

[lowc]

??dont understand what you are tyrin to say there

 

[jlunde15]

Ok, I've a 92 EVTM in front of me.

under power distribution the red + starts at the battery (of course) and goes to the starter, then on to the common side of the engine compartment fuse panel. According to the book, no fuse linksbetween the battery and fuse panel. Fuse links are on a branch that goes to the alternator, don't worry about them yet. So the engine compartment fuse panel should be hot at all times. The red wire may go directly from the battery to the fuse panel, wiring diagrams can be a bit mis-leading at times. end result is still the fuse panel should be hot at all times. one of those fuses is the EEC Relay fuse, 30A, and power leaves it via a yellow wire (circuit 37), goes to a splice, then two wires continue on thru connectors to the IRCM pin 8 and EEC pin 1. both of those should be hot at all times, if the EEC relay fuse is good.
other fuses send power to the ignition switch and the instrument panel fuse box.
you stated things started working when power was applied via tester to the engine compartment fuse panel? that would indicate no power there. check connections at the battery, starter, and engine fuse panel. if that does n't work start following the wires physically.

damn, now I have a headache.


Perry

Update, I've looked at the wires, and have been unable to find any type of fusible link as was suggested in previous posts; that being said, I have also found no evidence of troubled, rusted, or cut wires.

Is there a relay or fuse somewhere before the underhood relay block (abs pump relay, fuel pump relay, radiator fan, etc.) that I might be missing that would cause a no power issue?

Keep in mind, please, that I have no interior lights or anything until I apply power via probe.

 

[jlunde15]

Ok, I've a 92 EVTM in front of me.

under power distribution the red + starts at the battery (of course) and goes to the starter, then on to the common side of the engine compartment fuse panel. According to the book, no fuse linksbetween the battery and fuse panel. Fuse links are on a branch that goes to the alternator, don't worry about them yet. So the engine compartment fuse panel should be hot at all times. The red wire may go directly from the battery to the fuse panel, wiring diagrams can be a bit mis-leading at times. end result is still the fuse panel should be hot at all times. one of those fuses is the EEC Relay fuse, 30A, and power leaves it via a yellow wire (circuit 37), goes to a splice, then two wires continue on thru connectors to the IRCM pin 8 and EEC pin 1. both of those should be hot at all times, if the EEC relay fuse is good.
other fuses send power to the ignition switch and the instrument panel fuse box.
you stated things started working when power was applied via tester to the engine compartment fuse panel? that would indicate no power there. check connections at the battery, starter, and engine fuse panel. if that does n't work start following the wires physically.

damn, now I have a headache.


Perry

Ok, Perry, thanks for the information, and thanks to all for the help; however, I have not been able to devote any time as of late to fixing the car. Tax season is pretty brutal. After April 15th I'm hoping I might be able to start working on it again. I'll post again with my findings when I get a chance to get back under the hood.

 

[jlunde15]

Thanks, Perry for the help. Turns out it wasn't the IRCM, just like you said. I replaced the positive wire coming from the battery to the starter and problem solved. Thanks for your help!!