Check engine light
03-12-2009, 01:02 PM
#1
Junior Member
Thread Starter
Join Date: Mar 2009
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
Check engine light
1997, standard, 4.2L
CEL comes on, i scan the PCM, it says low voltage on Engine Coolant Temp sensor. I change it (disconnect battery too). CEL comes on. I pull the PCM, clean the PCM connector, clean the sensor connector, test the resistance of the sensor all the way back to the PCM connector (checks out), wiggle everything to make sure resistance reading does not change (okay). Put back together, drive it and CEL on.
Another important hint: When I disconnect the battery (effectively resetting the PCM), the engine runs perfect. Right after CEL comes on, engine runs rough, i.e. when accelerating quickly, there is some bucking that occurs; bad gas/air/spark mixture i'm pretty sure.
Tonight i will check the actual analog voltage the sensor puts out, if this is inline with what it should be, is replacing the PCM the next logical step?
How much should i spend?
CEL comes on, i scan the PCM, it says low voltage on Engine Coolant Temp sensor. I change it (disconnect battery too). CEL comes on. I pull the PCM, clean the PCM connector, clean the sensor connector, test the resistance of the sensor all the way back to the PCM connector (checks out), wiggle everything to make sure resistance reading does not change (okay). Put back together, drive it and CEL on.
Another important hint: When I disconnect the battery (effectively resetting the PCM), the engine runs perfect. Right after CEL comes on, engine runs rough, i.e. when accelerating quickly, there is some bucking that occurs; bad gas/air/spark mixture i'm pretty sure.
Tonight i will check the actual analog voltage the sensor puts out, if this is inline with what it should be, is replacing the PCM the next logical step?
How much should i spend?
