Help with PCM fuse that keeps blowing Electrical Issue

[Toolsplusmore]

i am pulling my hair out at this point. I took the car to the drag strip made my first pas and the car completely shut down around the 1000’ mark. I coasted the car off the track and found that the 40 amp PCM fuse was blown. I replaced it with the headlight fuse and it started right up and drove back to the pits.

I played with it for a bit in the pits and decided to attempt another pass. Car started up drove to the pits did the burn out staged launched and at the 1-2 shift the car died again. Coasted to a stop replaced the fuse again and started back up drove to the trailer and headed home. Once I got home as soon as I got the car un-strapped turn the key to run the fuse blows.

I have unplugged all the transmission sensors, oxygen sensors, cop connectors, injector connectors, maf, still no change. I have a power probe circuit tracer and it shows short to ground with the key in the on position.

I have swapped out the CCRM with no change. If the CCRM or PCM are unplugged the status light on the power probe switch to open circuit so that was of no help.

I have checked the radio RF isolaters and they are not grounded out anywhere.

I have taken the pcm out and inspected the board and see no obvious burned or bad spots and have checked each pin on the PCM to see if any were ground out and the only one showing ground is the pin that is supposed to bbe grounded.

I honestly do not know what to do at this point and am looking for suggestions on how to find the short or ground fault. Please help!!

 

[Terminator Dave]

i am pulling my hair out at this point. I took the car to the drag strip made my first pas and the car completely shut down around the 1000’ mark. I coasted the car off the track and found that the 40 amp PCM fuse was blown. I replaced it with the headlight fuse and it started right up and drove back to the pits.

I played with it for a bit in the pits and decided to attempt another pass. Car started up drove to the pits did the burn out staged launched and at the 1-2 shift the car died again. Coasted to a stop replaced the fuse again and started back up drove to the trailer and headed home. Once I got home as soon as I got the car un-strapped turn the key to run the fuse blows.

I have unplugged all the transmission sensors, oxygen sensors, cop connectors, injector connectors, maf, still no change. I have a power probe circuit tracer and it shows short to ground with the key in the on position.

I have swapped out the CCRM with no change. If the CCRM or PCM are unplugged the status light on the power probe switch to open circuit so that was of no help.

I have checked the radio RF isolaters and they are not grounded out anywhere.

I have taken the pcm out and inspected the board and see no obvious burned or bad spots and have checked each pin on the PCM to see if any were ground out and the only one showing ground is the pin that is supposed to bbe grounded.

I honestly do not know what to do at this point and am looking for suggestions on how to find the short or ground fault. Please help!!

A 40A fuse blowing is ALLOT of current! Can you post the part of the schematic that leads to the PCM? There is nothing on inputs or outputs that will cause this. They are low input pulses and 5V or 12V TTL levels. Either the PCM has one hell of a short, or most likely, you have a short on the wire leading to the B+ (12V)line of the PCM. When you say you shifted 1/2 gears, there's allot of torque and forward motion going on. Maybe you have a wire with insulation bad? Something is causing a 40A short.

Sent from my 2PS64 using the svtperformance.com mobile app

 

[hotcobra03]

what fuse #.


f3,f4,f5,f6,f12 are 40amp.

f6 was my guess

 

[Terminator Dave]

Yes. Please let us know exactly what the fuse number is, although from your description, it can only be one. I keep forgetting I have the manual too.

 

[hotcobra03]

I'm

Yes. Please let us know exactly what the fuse number is, although from your description, it can only be one. I keep forgetting I have the manual too.

im also waiting.
f1-26 30amp is for pcm and is hot at all times.
he says his blows after turning key.
than the 40s do other than pcm

 

[Toolsplusmore]

Sorry I made a mistake in my original post. It is the F1 26 fuse the 30 amp PCM not a 40.

 

[Terminator Dave]

Guys. Is it just my copy of the service manual, but I can't find a table of contents, etc. Am I missing something? I'd like to see this fuse, input to it, output from it, without looking through 4000+ pages.

 

[Roots-type]

#26 30a fuse is the one that will blow when you turn the key if you have a connection issue with a noise suppressor on the back of one of the cylinder heads.

 

[Toolsplusmore]

I have unplugged both noise suppressors in the fuse still blows immediately upon turning the key to on.

 

[hotcobra03]

Guys. Is it just my copy of the service manual, but I can't find a table of contents, etc. Am I missing something? I'd like to see this fuse, input to it, output from it, without looking through 4000+ pages.

wrong book..that is not the 1 for wiring.what wiring it has is a quick reference.
but 4299 is the page that shows f26
you need to down load the pc version.

I recall a few threads on f1-26 blowing

 

[hotcobra03]

than see pg 4282
.red wire..

 

[Roots-type]

I have unplugged both noise suppressors in the fuse still blows immediately upon turning the key to on.

When this happened to me the passenger side one came unplugged ever so slightly. Pushed down on it and heard it click into place and all has been well for 2.5 years. I'd plug them in if they're not already. Just me.

 

[*Jay*]

wrong book..that is not the 1 for wiring.what wiring it has is a quick reference.
but 4299 is the page that shows f26
you need to down load the pc version.

I recall a few threads on f1-26 blowing

Which book are you talking about, got a link to the "PC version"??? Would the sxhematics be in the big paper copy, I got that downstairs somewhere. I always assumed it had the same info as what I use on my phone from the terminator-cobra.com site.

 

[Terminator Dave]

Yes. I have the cell one and the PC. I haven't look at the PC version yet. The one on the cell has no TOC. You have to sift through every page. That's why I figured my copy was somehow missing some pages. OK. I'll look at the pages above. I'm done with my Terminator today. Man was it hot. We definitely talking about the PCM, right?

 

[hotcobra03]

also..are any other fuses blowing?
inside box?

 

[hotcobra03]

Yes. I have the cell one and the PC. I haven't look at the PC version yet. The one on the cell has no TOC. You have to sift through every page. That's why I figured my copy was somehow missing some pages. OK. I'll look at the pages above. I'm done with my Terminator today. Man was it hot. We definitely talking about the PCM, right?

I'm on android cell..small version has toc,and search function..
adobe Reader I use..

 

[hotcobra03]

Which book are you talking about, got a link to the "PC version"??? Would the sxhematics be in the big paper copy, I got that downstairs somewhere. I always assumed it had the same info as what I use on my phone from the terminator-cobra.com site.

pc version is in the same spot as small..click on the icon toward left of paragraph .

it is still pg by pg..however it has connector numbers,pics of connectors with what wires are in it.
connector location,and splices,and ground locations,
but it's all black and white..

the engine sensors are feed from a different fuse than f26..

with f26 out check for power on them..

 

[hotcobra03]

Online Resources | Monroe County Library System

password,,monroe

works on cell and is complete manual..you can save and copy pgs to cell..

than if on iphone..use tv..70inch screen is easy to read

 

[Toolsplusmore]

It is for sure the F26 PCM fuse and as mentioned before even with the suppressors unplugged it is still blowing indicating they are not the problem.

 

[hotcobra03]

Yes. I have the cell one and the PC. I haven't look at the PC version yet. The one on the cell has no TOC. You have to sift through every page. That's why I figured my copy was somehow missing some pages. OK. I'll look at the pages above. I'm done with my Terminator today. Man was it hot. We definitely talking about the PCM, right?