Coolant temp sensor

[Joe Dirte]

Both trucks basically same day. Both throwin code. Both are new sensors. Both just randomly decided to run like hammered dog ****. Also Both ain't readin right on scanner. Ones -40° others like -15°. I'm guessing it's a broken wire bein it's a one wire sensor. I lost the pics of the pcm plug IDs. Was thinkin just take the wire n wire it closer to the pcm instead of where it hooks to harness on top motor.

Oh yeah, Leeroy is a 96 with 350 and Huckleberry is 98 with 350 in case that matters.

 

[GoToGuy]

If you don't start with what your working on you might get skipped over. Which sensor, on manifold or left head? Finding the problem and fixing it, rather than hacking in another wire prevents future problems.

 

[Joe Dirte]

If you don't start with what your working on you might get skipped over. Which sensor, on manifold or left head? Finding the problem and fixing it, rather than hacking in another wire prevents future problems.

Ah forgot. It is the one on the left head.

 

[GoToGuy]

Same sensor, swap the wires over see if problem moves or goes away. Tells you if it's sensor or wiring.

 

[east302]

The one-wire sensor (on the head) is for the instrument cluster. The one by the thermostat (two-wire) is the one that the computer uses and the one that the scanner is reading a value from. If you swapped out the one on the head, it sounds like you’re looking at the wrong one.

 

[Joe Dirte]

The one-wire sensor (on the head) is for the instrument cluster. The one by the thermostat (two-wire) is the one that the computer uses and the one that the scanner is reading a value from. If you swapped out the one on the head, it sounds like you’re looking at the wrong one.

Oh OK. Everything i read said different. Shoulda known as Ganges worked fine. Thanks.

 

[someotherguy]

Where you reading that the one in the head is for the PCM? Stop reading there. The one in the intake manifold is what reports to the PCM.

The sensors work on resistance, the more resistance the colder temp indicated. -40F is typical for a completely failed sensor, and -15F isn't far behind. That is, of course, if your ambient temps are notably higher and you're not somewhere that it's actually those temps at the moment. Yep, it will richen the fuel mixture to the point it'll fuel foul your plugs.

Seems a strange coincidence both of your trucks are doing this at the same time, though. But if they're old, they're old; they tend to go bad gradually and you don't notice until they get really bad.

Also, look for your mouse friends to have damaged some wiring. Bad grounds on the intake near the thermostat for example.

Richard

 

[Joe Dirte]

Where you reading that the one in the head is for the PCM? Stop reading there. The one in the intake manifold is what reports to the PCM.

The sensors work on resistance, the more resistance the colder temp indicated. -40F is typical for a completely failed sensor, and -15F isn't far behind. That is, of course, if your ambient temps are notably higher and you're not somewhere that it's actually those temps at the moment. Yep, it will richen the fuel mixture to the point it'll fuel foul your plugs.

Seems a strange coincidence both of your trucks are doing this at the same time, though. But if they're old, they're old; they tend to go bad gradually and you don't notice until they get really bad.

Also, look for your mouse friends to have damaged some wiring. Bad grounds on the intake near the thermostat for example.

Richard

I was planning on checking the wiring today, especially the grounds. Last time I drove Leeroy to town he ran great as usual then all of a sudden started bouncing the RPMs n stumblin. Didn't see any mouse damage last time I was under the hoods. Can't remember if I put a new one in Huck or not but if i did it was most likely from Napa, the only parts store in almost 20 mile radius. I do know my mechanic friend said not to run any napa electronics. He's had nothin but problems with em since they switched supplier a few years ago. I'll be either ordering Delcos n hopin I get Delco or I'll grab a few from my friends junkyard next time I'm there.

 

[someotherguy]

I was planning on checking the wiring today, especially the grounds. Last time I drove Leeroy to town he ran great as usual then all of a sudden started bouncing the RPMs n stumblin. Didn't see any mouse damage last time I was under the hoods. Can't remember if I put a new one in Huck or not. I do know my mechanic friend said not to run any napa electronics. He's had nothin but problems with em since they switched supplier a few years ago. I'll be either ordering Delcos n hopin I get Delco or I'll grab a few from my friends junkyard next time I'm there.

Save yourself the trouble and skip the used coolant temp sensors. Consider them wear items.

Richard

 

[Joe Dirte]

Save yourself the trouble and skip the used coolant temp sensors. Consider them wear items.

Richard

But they're FREEEE hahaha