5.0ray

Had roommate help me jump my car, big mistake!!! He hooked up the cables wrong on my car and some wires started smoking.

After disconnecting and trying to start hooked up the right way it started, but would not stay on when cables are disconnected. Is that just the alternator or is there something else to check or replace? checked all fuses in car is there anymore to check in engine compartment?

mjr46

check the battery/ have it tested, may have shorted a cell in the battery and shorted alt and or taken out a fusible link or two

ttocs

electronics works with smoke the same way your motor works with gas. When you let the smoke out, it is very hard to put back in. Def check your fusable links and go get your alt tested.

projectresto83

I would say start with the battery then the alternator.....since it did start and run I would say most of the fusible links are good BUT that doesn't mean you didn't blow a couple like Mjr said.

projectresto83

5.0ray

Thanks guys I tested battery and somehow lucked out and batt was fine. Started car with jumpers on and tested alt, no juice coming from it, looks like I fried that, going to replace it asap and I'll let ya know the outcome.

Kyle Campbell

know this is an old thread, but having the same problem after jumping with reverse polarity (actually melted the cables). difference with me is the battery, alternator, fuses, and fusible links all tested and are ok. smoke was released from inside the car, which i thought was odd. thinking it may be computer, but saw another post stating that if car starts with SPOUT removed then it's the computer, otherwise computer is fine. removed spout and no change.

fuel pump pressurizes the lines, car turns over, i am getting a spark (though it is weak, likely due to troubleshooting/flooding), but car does not start. everything is stock except the after market turbo.

any thoughts welcome!

wbrockstar

One thing that's been known to occur when the cables are connected backwards is damage to the signal return trace on the ECU circuit board.The signal return trace (pin 46) is the power ground circuit used by the ECU & every sensor on the vehicle that shares the black/white wire (act,ect,map/bp,evp,tps,nss, ngs, css) These sensors will not function correctly if the ecu trace for this wire is damaged inside the ECU.Pin 46 wire also runs to the diagnostic port.This wire is the ground thats used to trigger a scanner to run the code tests,so if the trace is damaged,the scanner wont initiate the test.The normal connection method used when using the diy jumper wire method to initiate the code tests wont function either.A different connection method can be used to trigger the test though & if the test will only initiate using this method,it also verifies the trace is damaged on the ECU circuit board.Here are a couple ways to test the signal return trace.
1) Try running codes using a jumper wire.Connect the jumper between the STI terminal and the Signal Return terminal then turn the key on to see if the check engine light starts flashing codes.If it does,the signal return trace is ok.However,if the cel is isnt flashing at all,turn the key off and do this: Leave the jumper connected to the STI terminal,but move the other end of it directly to chassis ground or to the neg battery post then turn the key on.If the cel starts flashing & you get codes for the tps,bp,ect,act & evp sensors,this verifies the signal return trace is burnt open on the ECU board.
2) Backprobe the ECU harness plug with meter leads or pierce each wire for the following pins using a needle (40,46,60) Use your multimeter to test these pins by touching the meter leads to the needles you used (if you used that method) Test between pin 46 & 40 then 46 & 60 with your meter set to ohms.Both tests should read 1.5 ohms or less.If the readings are higher than this or the meter reads OL or Infinite the trace is burnt open.If it is damaged, you can fix it easy by soldering a piece of 32ga or similar gauge wire across the open trace.If the trace is ok,it still would be a good idea to remove the ECU from the kick panel anyways,to check the capacitors.They can sometimes suffer damage to from the reverse polarity mistake. There are 3 of them greenish blue in color. Look for buldging,leaking,broken or eroded posts,burnt spots or electrolytic solution dripping on the board &/or eroding the board/trace.
The pictures below show the damaged & repaired trace.Make sure to check both sides of the board also.


Burnt trace

Repaired trace

Capacitor pictures







Diagnostic port for codes

Buck Sergeant

5.0ray, all suggestions here are very valid. I would strongly suggest buying a new alternator. I have yet to see a alternator "diode bridge" that could survive reverse polarity. Suggestion, put a alternator on your Christmas list.

Kyle Campbell

wbrockstar, first off...no idea how you saw that break! mine is a little different unfortunately, '95 SVT. some corrosion, but nothing that appears abnormal or burnt (mind you I am by no means an electronics engineer).

my OBDII has never worked on this vehicle, so before I dig into method 2 can you help me to understand where i can find the pin numbers and if they are valid for this model? does the computer need to be plugged into the car and wires pierced since i'm just checking resistance?

zoomed in on corrosion

inside

back side


Buck Sergeant, bench tested alternator and it checked out fine. i also have continuity across the fusible link that is supposed to protect the alternator for this very situation.