is my ecm bad?


jsmith93
01-05-2016, 02:12 PM
I have a 2001 Chevy Impala my grandfather hooked the jumper cables up backwards to it. It will not start now, I think the ecu is bad is there any way to test it to see if it is bad? I replaced the alternator and the battery so I know it is not either of those. The radio, clock, all the lights still work, it just won't turn over. Any help would be appreciated.:banghead:

brcidd
01-05-2016, 05:52 PM
Look at every fuse in underhood fuse block-- probably one of those big fuses is toast--

jsmith93
01-06-2016, 12:30 PM
I've checked every fuse and tried putting new fuses in and not one is blown. I can start it by using a screw driver to jump the solenoid but it will only stay running for 2-3 seconds then will cut off.

Blue Bowtie
01-06-2016, 07:23 PM
Disconnect the battery overnight, which is coincidentally long enough to take it into a warmer place and charge it fully. Reinstall/reconnect the battery, insert the ignition key and turn it to RUN (not Start). Observe the "Check Engine" light as the ignition is first turned on. Describe what it does.

Tech II
01-06-2016, 07:23 PM
It is quite possible, it's the PCM, but it could be a few other things too....

How did you check the fuses? Just by looking at them, or checking for power with a test light, with the key on?

Did you also check the large fuses like Batt1, Batt2, and Batt3(all 60 amp fuses) like brcidd asked? Do they all have power to them?

Do you know if your car has PassLock or PassKey, for SECURITY?

Blue Bowtie
01-06-2016, 09:02 PM
Passlock (not PassKey or VATS), CL2 bus, BCM, RAP module, radio, I/P, EBCM, door modules, and DERM for the SIR are all involved. Most modules have diode protection and MOVs in their power supplies, as does the PCM, but not all of the I/O is protected for polarity.

If the PCM does the MIL bounce on energization, we'll know that the NVRAM is good (at least the checksum is valid), its power supply is good, and processor is good. The rest is in question, but without the bounce it may be history. If the PCM behaves on power-up, the rest of the modules on the bus may behave, including the BCM.

I'd suggest powering up the system without starting the engine, testing accessories, radio, HVAC, and watching the warning lamps and instrument cluster, taking note of the warnings, indicators, and what doesn't operate properly. Also determine if the fuel pump runs a two-second prime cycle when the ignition is turned on.

Then power it down. Recharge the battery if necessary, then perform the procedure again, attempting to start the engine after observing the indicators and warnings.

jsmith93
01-06-2016, 11:31 PM
thanks to all...

Also part of my key is stuck in my ignition (broken key) and has been for about a month now. Could that cause it to do this? It's been running fine since then, I had no problems with it until the cables were put on backwards. I just have to jump it off sometimes when it gets very cold out... I am only asking this for my grandfather he is convinced the jumper cables being put on backwards had nothing to do with this.:disappoin

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