OleGreen93
Newbie
I bought my 92 c1500 with 100k miles last month in early September. It has the 700r4 transmission and shifted perfectly while it was still warm last month. Now that outside temps are cooling down I've noticed that it takes around 10-15 minutes of driving for the TCC lockup to occur at speeds 45+ mph. When the TCC lockup does occur, it will stay locked for a little while and then unlock without anything changing such as road conditions or throttle position. It then takes a little while before it locks again. I swapped the brake light switch from my other gmt400 and nothing changed.
My main question is what are the conditions for the truck to engage the TCC lockup at highway speeds? Does engine temperature have an effect on TCC lockup? The reason I ask is because after my drive to work this morning in mid 50s weather which is only about 4 miles but truck was running for around 25 minutes, the temp gauge in the cluster is barely showing over 100 degrees. I brought my digital thermometer with me and the temp switch in the driver side cylinder head was showing around 165 degrees. The temp sensor in the intake for the computer was around 145 degrees. The thermostat housing was also at 145 degrees and upper radiator hose was at about 122 degrees.
My concern is that maybe this truck has a lower rated thermostat installed and if the TCC lockup is tied to engine temps that this might be why it is taking the TCC lockup longer to engage and not staying engaged at highway speeds. The fluid is at the correct level and looks to be in good shape although i do not know if the transmission has been serviced before.
My main question is what are the conditions for the truck to engage the TCC lockup at highway speeds? Does engine temperature have an effect on TCC lockup? The reason I ask is because after my drive to work this morning in mid 50s weather which is only about 4 miles but truck was running for around 25 minutes, the temp gauge in the cluster is barely showing over 100 degrees. I brought my digital thermometer with me and the temp switch in the driver side cylinder head was showing around 165 degrees. The temp sensor in the intake for the computer was around 145 degrees. The thermostat housing was also at 145 degrees and upper radiator hose was at about 122 degrees.
My concern is that maybe this truck has a lower rated thermostat installed and if the TCC lockup is tied to engine temps that this might be why it is taking the TCC lockup longer to engage and not staying engaged at highway speeds. The fluid is at the correct level and looks to be in good shape although i do not know if the transmission has been serviced before.