Help! Bouncing idle then Dies.

[SammieH]

Have you checked the neutral safety switch connector?

I have not. What makes you suspect that? Will check and clean it tonight. Thanks

 

[Malleus]

83,84,85 DTCs are TCM communications errors. The TCM is separate from the ECM in the 2nd generation 80 series.

@Fj80oregon is correct about the idle problem, though. The IACV is a pernnial problem. You can try to clean it; the two function tests are in the service manual – use the 1993 (or '94) version. I've never had any luck cleaning one and restoring its function, after it failed, though. The 2nd gen IACV is NLA; if you need a replacement, you will have to get a 3rd gen part.

 

[Fj80oregon]

83,84,85 DTCs are TCM communications errors. The TCM is separate from the ECM in the 2nd generation 80 series.

@Fj80oregon is correct about the idle problem, though. The IACV is a pernnial problem. You can try to clean it; the two function tests are in the service manual – use the 1993 (or '94) version. I've never had any luck cleaning one and restoring its function, after it failed, though. The 2nd gen IACV is NLA; if you need a replacement, you will have to get a 3rd gen part.

I purchased a new IACV for a 97 and swapped it in my 94 and it fixed my low idle issues. I also cleaned the old one and it function tested perfectly FSM and passed but was still giving me a low idle.

 

[SammieH]

I purchased a new IACV for a 97 and swapped it in and it fixed my low idle issues. I also cleaned the old one and it function tested perfectly FSM and passed but was still giving me a low idle.

Interesting. How low was your idle, and was it constantly low? Mine will sometimes hover around the high 5s and then bring itself slowly back to 650. Sometimes it says low. No real pattern. Will idle around 590 at a stop and when I put it in neutral it often comes back up. I will try cleaning but will probably end up buying new. Thanks

 

[SammieH]

83,84,85 DTCs are TCM communications errors. The TCM is separate from the ECM in the 2nd generation 80 series.

@Fj80oregon is correct about the idle problem, though. The IACV is a pernnial problem. You can try to clean it; the two function tests are in the service manual – use the 1993 (or '94) version. I've never had any luck cleaning one and restoring its function, after it failed, though. The 2nd gen IACV is NLA; if you need a replacement, you will have to get a 3rd gen part.

I read that these codes are tcm issues but I’ve also read on here that the only way to fix the issue is with a new Ecu. Mine had already been replaced and I’m assuming it was to clear the codes. Are you suggesting that they would have nothing to do with the idle issues I’m having? Thanks

 

[Malleus]

I purchased a new IACV for a 97 and swapped it in my 94 and it fixed my low idle issues. I also cleaned the old one and it function tested perfectly FSM and passed but was still giving me a low idle.

Same here. Cleaned, retested. Passed both tests. Still didn't work.

 

[Malleus]

I read that these codes are tcm issues but I’ve also read on here that the only way to fix the issue is with a new Ecu. Mine had already been replaced and I’m assuming it was to clear the codes. Are you suggesting that they would have nothing to do with the idle issues I’m having? Thanks

Replacing the ECM on a 1993 model is not guaranteed to solve a communication problem with the TCM; they are two seperate, disctinct computers. The 3rd gen (1995-1997) has integrated ECM/TCM computers.

I suggested you check your NSS, because that's an easy connection to get to. The engine harness to transmission harness connectors are on top of the starter, directly beneath the pesky heater hose (water bypass no. 1). They are not the easiest to get to, or check. Even with the starter out, they're a PITA. The only time there is easy access to them is when the intake manifolds are out.

If there has been a bypass hose leak (very common), there will be corrosion in the connector housings (there are two of them). The most common result is a loss of PRNDL2 lights.