96 K3500 454 coolant temp sensor

[run96k3500]

On my 96k3500 with the Vortec 454 is has a 1 wire coolant temp sensor on the driver and passenger side of the engine. Where done the passenger side sensor connect to? There have been a few owners of my truck and it seems that last owner did reconnect the passenger side sensor and cut the wire. Can someone send me a pic and/or wiring diagram so I can reconnect it.

 

[someotherguy]

Hopefully someone can come up with this one - check the downloadable service manuals here. A while back I was looking for the exact same info for my '96 C3500 7.4 - that's a temperature switch by the way, for the auxiliary cooling fan.

On my truck it looked like the wire ran up to the passenger/front of the intake manifold where there was a little white splice 'box' for lack of a better term. The wires were damaged and cut off so I couldn't tell exactly how it should reconnect, and at the time I was asking, nobody else seemed to know, either.

Richard

 

[run96k3500]

Hopefully someone can come up with this one - check the downloadable service manuals here. A while back I was looking for the exact same info for my '96 C3500 7.4 - that's a temperature switch by the way, for the auxiliary cooling fan.

On my truck it looked like the wire ran up to the passenger/front of the intake manifold where there was a little white splice 'box' for lack of a better term. The wires were damaged and cut off so I couldn't tell exactly how it should reconnect, and at the time I was asking, nobody else seemed to know, either.

Richard

I haven’t been able to locate the wiring diagram. So hopefully someone knows.

 

[smokymtn65]

the one wire on mine, goes from passenger head. to top of intake and connects to a wire in the a/c harness.

 

[someotherguy]

the one wire on mine, goes from passenger head. to top of intake and connects to a wire in the a/c harness.

Yeah, can't say 100% for sure on a GMT400 but it is typical of aux fan setups that they are triggered by coolant temp and/or A/C compressor head pressure, so it makes sense that A/C wiring is included in this circuit.

Richard

 

[Supercharged111]

Yeah, can't say 100% for sure on a GMT400 but it is typical of aux fan setups that they are triggered by coolant temp and/or A/C compressor head pressure, so it makes sense that A/C wiring is included in this circuit.

Richard

Seeing how the computer controls the aux fan, I would think it'd just use the ECT for that.

 

[someotherguy]

Seeing how the computer controls the aux fan, I would think it'd just use the ECT for that.

I think this setup varies over the year models. On my '96 7.4 it did not appear to be PCM controlled.. but then again, the wiring was damaged so the fan was inoperable. I think it was 454CID that mentioned his truck didn't have the passenger side temp switch? He's got a .. '98 or '99 IIRC. Could be way off-base here as it's been 10 years.

Richard

 

[Carlaisle]

The temperature sensor should be in the driver's side head, not the passenger side head. As far as I know, the factory never installed one in the passenger side and never one in both heads. The sensor in the driver's side is what feeds the dash gauge. It goes into the engine harness on top of the engine nearby. The ECM uses a different sensor near the thermostat. The info from the sensor near the thermostat is what the ECM uses to control the auxiliary fan and all other engine control functions.

 

[smokymtn65]

I think po was to lazy to move back to driver side on mine and.cut and spliced longer wire when it was rebuilt.

 

[someotherguy]

The temperature sensor should be in the driver's side head, not the passenger side head. As far as I know, the factory never installed one in the passenger side and never one in both heads. The sensor in the driver's side is what feeds the dash gauge. It goes into the engine harness on top of the engine nearby. The ECM uses a different sensor near the thermostat. The info from the sensor near the thermostat is what the ECM uses to control the auxiliary fan and all other engine control functions.

As far as you know doesn't count for much in this example. The dash gauge temperature sender is indeed in the driver's side head. The auxiliary fan switch, when equipped, goes in the same position but on the passenger side head. We've already covered that in this thread for one's edification. (There are other examples, like some TPI engines have the aux fan switch installed in the block, passenger side, but obviously not relevant to GMT400 trucks.)

Let me assist a little further - go to gmpartsdirect, look up a 1996 C3500 with a 7.4, go to cooling system section, fan, scroll down past the mechanical clutch fan and note the electric fan setup that mounts ahead of the condenser. See the part # 12554254 (discontinued) referred to as a "fan switch" ? That's what sits in the passenger side head on that particular application, and controls that fan.

Richard