71 ls-5 temp sender wiring

[Rick Garrett]

On the 71 LS-5 temp sender there are two prongs. These are marked R and G I suppose this is red and green. I was able to located the green wire going into the guage harness, but what is supposed to go on the R side?

thanks

Rick

[Jim Kammerer]

Re: 71 ls-5 temp sender wiring

The green wire goes to one terminal and another wire is connected to the connector and goes to the other terminal. It is just jumper wire. Not sure why.

[Jim Kammerer]

Re: 71 ls-5 temp sender wiring

The green wire goes to one terminal and another wire is connected to the connector and goes to the other terminal. It is just jumper wire. Not sure why.

[Rick Garrett]

Re: 71 ls-5 temp sender wiring

thanks Jim, does anyone know why the jumper wire is present?

[Rick Garrett]

Re: 71 ls-5 temp sender wiring

thanks Jim, does anyone know why the jumper wire is present?

[Terry M.]

Re: 71 ls-5 temp sender wiring

Just a little terminology first - then the answer.

The temp sender is in the left hand (drivers side) head and is a single wire.

The swithc (GM terminology) in the right hand head is for the CEC (Combined Emissions Control) system. The same switch is used for the TCS (Transmission Controlled Spark) system in 1970 & 1972.

There is a detailed description of these systems in both the 1970-1972 Technical Information Manual & Judging Guide and the 1968-1972 Operations & PV Manual. There is also the same in the 1971 Chassis Service Manual under the Emissions section (I think it is 6M, but again my memory may be wrong. It is near there anyway). The down side of the Service Manual is that it lists all Chevrolet products and you have to sort Corvettes out of that bunch.

The short explaination is that switch has a high temperature and low temperature component. It makes a ground below about 82 degreed F and above 240 degrees F (don't hold me to the exact numbers. My memory is bad. If the exact numbers are important to you check the Chassis Service Manual or the PV manual).

When grounded it energises the solenoid on your carburator and that sends vacuum to the distributor. That increases engine speed about 300-500 RPM. There is more to the system, involving the transmission; but you asked only about the temperature switch. There is also theory behind why it operates that way, and why you want it to operate the way it was designed. This answer is getting too long for all that. If you want all that just ask, but trust me you want it to work the way it was designed if you have the original carb & distributor.

BTW: The advise Jim gave you about the green wire jumper is correct.

Terry McManmon

[Terry M.]

Re: 71 ls-5 temp sender wiring

Just a little terminology first - then the answer.

The temp sender is in the left hand (drivers side) head and is a single wire.

The swithc (GM terminology) in the right hand head is for the CEC (Combined Emissions Control) system. The same switch is used for the TCS (Transmission Controlled Spark) system in 1970 & 1972.

There is a detailed description of these systems in both the 1970-1972 Technical Information Manual & Judging Guide and the 1968-1972 Operations & PV Manual. There is also the same in the 1971 Chassis Service Manual under the Emissions section (I think it is 6M, but again my memory may be wrong. It is near there anyway). The down side of the Service Manual is that it lists all Chevrolet products and you have to sort Corvettes out of that bunch.

The short explaination is that switch has a high temperature and low temperature component. It makes a ground below about 82 degreed F and above 240 degrees F (don't hold me to the exact numbers. My memory is bad. If the exact numbers are important to you check the Chassis Service Manual or the PV manual).

When grounded it energises the solenoid on your carburator and that sends vacuum to the distributor. That increases engine speed about 300-500 RPM. There is more to the system, involving the transmission; but you asked only about the temperature switch. There is also theory behind why it operates that way, and why you want it to operate the way it was designed. This answer is getting too long for all that. If you want all that just ask, but trust me you want it to work the way it was designed if you have the original carb & distributor.

BTW: The advise Jim gave you about the green wire jumper is correct.

Terry McManmon

[Rick Garrett]

Re: 71 ls-5 temp sender wiring

did the 71 LS-5 engines have the switch in the right side head also?

[Rick Garrett]

Re: 71 ls-5 temp sender wiring

did the 71 LS-5 engines have the switch in the right side head also?

[Jim Kammerer]

Re: 71 ls-5 temp sender wiring

MIne is on the right side. Jim

[Jim Kammerer]

Re: 71 ls-5 temp sender wiring

MIne is on the right side. Jim

[Rick Garrett]

Re: One more question?

I think from what Terry is saying, that a sensor is in the left head and a switch in the right. Are the switch and the sensor the same thing? I dont see a listing for that part? Where does the switch wire into?

[Rick Garrett]

Re: One more question?

I think from what Terry is saying, that a sensor is in the left head and a switch in the right. Are the switch and the sensor the same thing? I dont see a listing for that part? Where does the switch wire into?

[Jack H.]

Re: 71 ls-5 temp sender wiring

Switch is double pole single throw. When engine is cold makes contact to ground. Grounding activates CEC relay to engage carb mounted solenoid and boost engine RPM (fast warm-up and improved cold drivability).

When engine temp hits hits normal operating range, both poles are open circuit and CEC relay releases carb solenoid for normal curb idle RPM.

When engine is in overheat range, second pole is contacted. This is wired to the first pole to give contact closure to ground again. Makes CEC relay engage carb solenoid and raise RPM to suck more air through radiator (answer to overheat relief in stop/go traffic in summer).

Complete description of the emission system is given in 1971 Chevy Chassis Servive Manual. But, system was 11th hour intro to MY change over and there is little/no troubleshooting info in the '71 CSM. For this you go to '72 CSM and look up V-8 passenger car.

What! Why look up passenger car? Simple, system was a 'bomb' in terms of HP Corvette ownership community and had a one year lifespan. Appears GM 'burned' the balance of inventory on 1972 LP V-8 engines (Nova, Etc.).

[Jack H.]

Re: 71 ls-5 temp sender wiring

Switch is double pole single throw. When engine is cold makes contact to ground. Grounding activates CEC relay to engage carb mounted solenoid and boost engine RPM (fast warm-up and improved cold drivability).

When engine temp hits hits normal operating range, both poles are open circuit and CEC relay releases carb solenoid for normal curb idle RPM.

When engine is in overheat range, second pole is contacted. This is wired to the first pole to give contact closure to ground again. Makes CEC relay engage carb solenoid and raise RPM to suck more air through radiator (answer to overheat relief in stop/go traffic in summer).

Complete description of the emission system is given in 1971 Chevy Chassis Servive Manual. But, system was 11th hour intro to MY change over and there is little/no troubleshooting info in the '71 CSM. For this you go to '72 CSM and look up V-8 passenger car.

What! Why look up passenger car? Simple, system was a 'bomb' in terms of HP Corvette ownership community and had a one year lifespan. Appears GM 'burned' the balance of inventory on 1972 LP V-8 engines (Nova, Etc.).