Reverse Polarity Desperation

[UNO_RACING]

Well I think I fried my ECU for my thorttle body injection. Yesterday, I needed to jump my truck to put it back into the garage. I wasn't paying attention and I hooked up the jumper cables backwards on my truck. Yes, I know stupid---I not the sharpest tool in the shed.

I let the battery charge for a couple miniutes and heard the 50amp fuse blow to the wiring harness. Although the wiring harness was protected, the ECU, I believe, was not becasue it is directly wired up to the battery for power.

After replacing all the fuses, the truck turns over and everything electrical works, but its not getting spark or fuel. I checked the TBI wiring harness to see if there were any fault protections in place and there's no fuses in the lines. Am I screwed with the entire wiring harness or sensors; there's no signs of cooked wires on the harness? Hopefully I can get away with replacing the ECU.

Also,I wondering if there's any conseqnetial damage that could have been done to the HEI distributor. What are your thoughts.

 

[Friendly Persuasion]

Your engine harness and sensors should be ok. The sensors send feedback to the ecm so unless the ecm turned on you should be ok.
Gavin

 

[BrianSanDiego]

I would think you'd be OK too.

Check for a cooked wire somewhere. Also, on most (all?) HEI distributors, all you need is one power wire going to the cap and it'll fire. Pretty easy test it for damage.

Do you have a wiring diagram for the connection to the ECU? Make sure you are even getting power to it. Or try just using a test light at the plug for the ECU, to at least know if its getting power that far at all.

Good luck,
B.

 

[Buckwheat]

24v battery

You basically created a 24v and however many amp battery when you connected the batteries in series, hence the fried circuit protectors, which saved the wiring, as intended. The fact the fuel pump is not working may be an indicator the ECM has failed, since the pump was run thru the ECM on early versions of EFI. My recollection is that was not the case on TBI but I don't know what your system entails. Check the pump relay, if there is one, because many systems require that to close before the distributor gets power. There must be something in the circuit to protect the ECM else it could fry everytime you turn the key on & get a voltage spike. Most OEM have an ECM fuse & it is surprising there was no protection for such a critical component. If the key was not on, the ECM circuitry may not have been grounded, so it is possible, though connected, it may not have been drawing any current.

 

[UNO_RACING]

I bought a remaned ecu at NAPA, put it in, and it wouldn't fire.

I decided to check the wiring harness again and determined that there are fuses in protectors that actually looked like relays. Guess what? One was blown---replaced, and truck fired right up.

I drive it around for a while and the truck is actually running much better than it ever has before. Prior to replacing the ECU it always had a miss at 3,700 RPM. I thought it could be fuel related, but it seems to have been the ecu.

Thanks to all that replyed.

Happy Thanksgiving!

 

[Vicm]

That is good to hear,
Your first post is not clear what has been done . There is not enough detail to even understand what the problem is or what rig is having the problem. I think you would had better responses , if you detailed it better. Anyway, thanks for posting.
Vic