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- Thanks for the clarification on the procedure. My concern is that if the coolant is at too hot when I crack open the reservoir cap that it will boil over. I have an IR thermometer and used it to confirm that the engine temp is NOT over operating temp when the warning message occurs. So I can follow the manual procedures exactly I need some help with details. When I do step 15 of the manual procedure (15. Cycle the engine RPMs from idle to 3000 in 30 second intervals until the coolant temperature reaches 99°C (210°F).) Do I use my IR thermometer and point it on the thermostat housing to confirm the coolant temp is at 210F? If yes and thermometer is showing 210F, then I turn off the engine and then immediately complete step #2….2.1-2.3?
The IR therometer is just to confirm the gauge reading, and if the gauge goes crazy while you are trying to burp the system, you can proceed with the thermostat reading....so you can get the system properly serviced. It will also confirm if the engine is indeed overheating.
You will obviously need help to proceed this way.
It is either a bad sensor or a “short to ground” on the signal wire anywhere between the PCM and the sensor…the ECT is a simple 2 wire thermistor circuit…if you were to remove the ECT sensor you will see -40 degrees with a scan tool or the temp gauge will go full cold looking at the gauge…if you were to jumper the 2 wires together at the connector it will go full hot…in your case the signal wire is chaffed somewhere and when the YELLOW signal wire goes from its normal 5 volts with the key ON to ground the temp maxes out…if you have a DVOM connect it the yellow wire and to ground…turn the key on and when you wiggle the harness and the 5 volts goes away there is your short…this is not a “ground” issue and you can’t go by “wiring looks fine”…as a new member ALWAYS let us know at a minimum what model year you have as wiring can change from year to year…just fill out your profile..and yes the PCM will start shutting off injectors when the ECT gets that high.
Rob, you're spot on, as always. You may remember I had this issue earlier this summer. I talked to you about it, and had just started back probing the ground for the sender when I saw the problem-shiny, bare copper wire strands! I got to thinking that-Hey, there was no issue before I loosened and pivoted the alternator. Put the alternator back in position and BAM, coolant went to 260° and the high speed fans were on!! I found that I had somehow pinched the ground wire when repositioning the alternator!! Some solder and shrink tubing was all it took to fix it. If I were the OP, I'd thoroughly inspect the wiring near the alternator. I'm sure I pinched that wire a few times over 22 years before I finally bared it. Carelessness!!! I hate when I make work for myself. DOH!!!!!!
Rob, you're spot on, as always. You may remember I had this issue earlier this summer. I talked to you about it, and had just started back probing the ground for the sender when I saw the problem-shiny, bare copper wire strands! I got to thinking that-Hey, there was no issue before I loosened and pivoted the alternator. Put the alternator back in position and BAM, coolant went to 260° and the high speed fans were on!! I found that I had somehow pinched the ground wire when repositioning the alternator!! Some solder and shrink tubing was all it took to fix it. If I were the OP, I'd thoroughly inspect the wiring near the alternator. I'm sure I pinched that wire a few times over 22 years before I finally bared it. Carelessness!!! I hate when I make work for myself. DOH!!!!!!
The OP's issue was resolved in July. This thread was continued by Mcourtneymobile......
