Chrysler Repair: 97 Chrysler Cirrus stalling at idle and stops, intake air temperature sensor, amp fuse

Question
Roland,
I have a 97 cirrus 2.5L V6. It is stalling at idle and sometimes when coming to a stop. The check engine light has come on and gives the following codes: 12 , 17 , 23.
12 is pcm has benn disconnected
17 is engine does not come up to temperature quickly enough
23 is to high a voltage on IAT Intake air temperature sensor.

I checked the iat and its resistance was high according to the book at 3000 ohm @200F so I'm going to replace that.

What bothers me is that the car cuts out at the same time the check engine light cuts off. The dealer talked about possibly replacing the PCM.
I saw in an earlier question the EGR Valve needed fixing or replacing. I can understand that would cause the stall but what causes the code 12 fault?

I need the car to pass emmisions in Maryland first then stop stalling at idle second.

Thank you

Colin  

Answer
Hi Colin,
I wouldn't contemplate replacing the PCM at this point.
The code 12 is saying that the direct battery input to the PCM has been disconnected sometime in the past 50 key cycles. If you haven't actually disconnected the battery then that would suggest to me that there is a flakey connection between the battery and the PCM. The suspected item would be 20 amp fuse #5 in the power distribution center. If it were loose or poorly connected in it's fuse socket or if the center wire were cracked and spontaneously opening and closing with heating and cooling of the wire then either of those would produce a shutdown like you described because that same circuit also provides power to the ASD relay, coil and contact sides (I'm uncertain what the latter is referring to). You could also check the red/tan wire from that fuse socket to pin 46 of the gray 40-way at the pcm for continuity and solidity against cable flexing. If the mil light goes off when the engine dies that could well be the result of something flakey in this circuit which causes the 12 code.
On the stalling out, since both the coolant temp sensor and the intake air sensor are involved in the mixture setting process if either or both were off-value you could be getting a wrong mixture. The 17 code could well mean that the sensor is not cutting down its resistance the way it should as the coolant heats (thus the pcm thinks it is taking too long to warm up the coolant) and also if the pcm thinks the coolant is truly cooler than it is you will get a too rich mixture. The same goes for the IAT. That would then produce a stalling condition. So I would remove and check both sensors in a pan of water with an accurate thermometer. My manuals for '95 and '96 give the same spec for both sensors: 0.6-0.8k ohms at 212, and 9-11k ohms at 77F.
If verifying and correcting those sensors doesn't solve it then I would check the egr valve stem for freedom of movement and see if it is closing all the way when idling. Let me know if you need more detail about its location, etc.
I suspect though that everything will work out for the smog inspection if you deal with the 12,'17, and 23 codes as described.
Roland
P.S. Please let me know how this turns out.