LT4 1996 LT4 overheating

[glefebv]

96 lt4 is overheating due to cooling fans not coming on. I have checked the passenger compartment fuse, it is good, I have checked the 2 maxi fuses and they appear good. also have checked the three relays and they appear to be good. I am thinking that the sending unit is the next component to verify good functionality. it appears to be pretty straight forward to remove, once I have it out how can i test if for proper operation? Thanks for any and all help in advance.

 

[Hib Halverson]

There is no "sending unit" which turns the fans on or off. The fans are controlled by the engine computer. There is a sending unit screwed into the left head which supplies ECT information to the ECM which the ECM uses, along with other parameters, to control the fans but, if that's failed, most likely the engine light would be on.

In the 96 Service Manual, on pages 6-639 to 6-644, there is a section of diagnostic steps to test the fan system and help you decide if the problem is with the fans, the relays, the wiring or the ECM.

I believe the information needed to "test" the sensor is in the FSM, too.

 

[glefebv]

Hello

There is no "sending unit" which turns the fans on or off. The fans are controlled by the engine computer. There is a sending unit screwed into the left head which supplies ECT information to the ECM which the ECM uses, along with other parameters, to control the fans but, if that's failed, most likely the engine light would be on.

In the 96 Service Manual, on pages 6-639 to 6-644, there is a section of diagnostic steps to test the fan system and help you decide if the problem is with the fans, the relays, the wiring or the ECM.

I believe the information needed to "test" the sensor is in the FSM, too.

Thanks for your comments Hib. I do have the FSM, in the table on page 6-639 step 3 call for "install scan tool". where do I get one of these and about what is the cost. also, where does one install the scan tool?

I'l look forward to your reply.

thank you, do take care & God bless, Gary

 

[ecss]

To see the engine coolant temperature as seen by the PCM you press the Gauges button on the driver information center until you see Coolant displayed in the dash cluster LCD. That is the main parameter the PCM uses to turn on and off the fans.

If you turn on the AC do the fans every come on?

What makes you believe the engine is over heating?