I have alot of issues with the truck running good when it's cold out, but as soon as the engine warms up, it won't shift into overdrive & just stays flat with the rpms running real high & reduced power (sluggish). It basically runs terrible when it's warm. Some people say it might be a coolant temperature sensor that's causing the problem. It has not thrown any codes. Does anyone know where this sensor is located and could it be the problem? Any help is appreciated.

It's likely the coolant sensor is your problem, it's located at the top of the water crossover, real easy to see and get to. Mine didn't throw a code when it was bad because it was till giving a reading, but it was giving a very low reading. Take a paper clip and bridge the leads in the connector that plugs into the sensor and if you can get into OD, it's the sensor.

So a faulty coolant Temp sensor can cause weird shifting and high rpm surging?

I thought it was my vac pump so I replaced that today with a TM but Im still getting weird shifting and High rom surging

It's likely the coolant sensor is your problem, it's located at the top of the water crossover, real easy to see and get to. Mine didn't throw a code when it was bad because it was till giving a reading, but it was giving a very low reading. Take a paper clip and bridge the leads in the connector that plugs into the sensor and if you can get into OD, it's the sensor.

Scan tool ,if available, is your friend. It will tell you what the sensor is saying.

On 97 anyone its on the Driver Side of the engine towards the very front down buy the first injector and glowplugs (even closer to the front) you'll see a brass looking gizmo threaded into the block. (Some threads still exposed on mine).

Not too expensive and mighta s well just throw a new one in there as they will go eventually, and accurate temps are a good thing. I had to replace mine when I bought it it wasn't working. Who knows when it failed or what temps the PO allowed it to get too.

Speaking of that, on test drives I had no shifting issues whatsoever with a non working CTS. Or perhaps it was still communicating with teh PCM, just not working on the gauge cluster.

On 97 anyone its on the Driver Side of the engine towards the very front down buy the first injector and glowplugs (even closer to the front) you'll see a brass looking gizmo threaded into the block. (Some threads still exposed on mine).

Not too expensive and mighta s well just throw a new one in there as they will go eventually, and accurate temps are a good thing. I had to replace mine when I bought it it wasn't working. Who knows when it failed or what temps the PO allowed it to get too.

Speaking of that, on test drives I had no shifting issues whatsoever with a non working CTS. Or perhaps it was still communicating with teh PCM, just not working on the gauge cluster.

You are speaking of the the coolant temp sender, correct? Not the coolant temp sensor? They are separate and serve different functions.

You are speaking of the the coolant temp sender, correct? Not the coolant temp sensor? They are separate and serve different functions.

I think he's taking about the coolant temp sensor the ECM reads and not the one that shows the temp on the factory gauge. There are 2 correct? The one that the ECM reads can cause weird shifting right?

So there are two different ones? Where is the one located that the ECM reads?

Thanks

So there are two different ones? Where is the one located that the ECM reads?

Thanks


SEARCH!!!!


J/K :p: I'm going to replace the sensor that the ECM reads. Hopefully it solves my problems

ECM-Coolant Temp Sensor for all 6.5TD's 94+. Replace when ses codes indicate sensor failure, vehicle fails to come out of warm-up mode (fast idle), damaged or as preventative maintenance. This is the two wire sensor that screws into thermostat crossover manifold. Installs in minutes. This sensor does not work your temp gauge. It is the temp sensor for the ECM (computer)

Coolant-Coolant temp sensor for the factory temp gauge. This is the one wire sensor located on the LH cylinder head. Replace if damaged or if your factory temp gauge reads erratic, or as preventative maintenance.

*These arent my words I copied and pasted this from somewhere*