Question
Good evening Roland!
Have a 95 cirrus that started intermittently bucking (to me it feels like the ignition shuts or for a second) or stalling it will start right back up a few months ago.
The check engine light has been on since we bought the car a few years ago but never had any drivability problems so I hadn’t had a chance to look into it.
I pulled the codes last weekend and ended up with eng71/p1496(5v out low), eng33(ac sensor input low), eng 32/p0112(charge temp voltage low), eng32/p0403(EGR solenoid circuit). Cleared the codes and they came right back. While vehicle is running the scanner was reporting 0volts from the IAT sensor. This car is OBD1 compliant with the DLC in the driver’s compartment.
Tonight I checked the resistance of the IAT sensor, and while I didn’t go through the full cold to warm range for resistance I was getting resistance in line with a warm condition. I checked all the sensor grounds(blk/lt blu) for opens or shorts back to PCM and everything was 0ohms. I then checked the voltage at the sensors (vio/wht) and the voltage was right at 5 volts with key on and running. I then checked voltage at the vio/wht at the pcm and read about 0.45volts(I’m thinking maybe I didn’t probe it well enough but the ground worked just fine…strange will double check tomorrow).
I’m going to do more investigating tomorrow evening but I wanted to see if you might have any thoughts or ideas of how I should proceed.
Any help is greatly appreciated.
Thank you
Randy
AnswerHi Randy,
The sensors listed by the fault codes all use the 5 volt supply so it is not surprising that all were implicated. The issue is which one is dragging down the voltage or has a short in its wiring that is dragging it down. I would monitor the violet/white 5 volt supply after disconnecting all of them, then try reconnecting each and monitoring the voltage when it is connected and also when you shake the wiring harness for it. One of them will hopefully reveal that it is the source of the issue. It would be good to also check the MAP and the TPS as they too use the 5V supply.
It would be good as well to check the mechanical function of the egr valve stem. It is seems to be sticky and not closing tightly by spring action when you lever it via the slot in the stem then spray some WD-40 on it where it enters the valve body.
Thanks for the very detailed and logical report on what you have done so far.
Roland
