Temp light help

Baker7888

Master Mechanic
Dec 3, 2021
392
28
Maine
Hey guys. See the pics. I know temp light is #3 on the cluster connector. Seems to be ckt #35 i am not great with these diagrams. Is there a fuse in this light circuit?
 

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pagrunt

Geezer
Sep 14, 2014
8,228
113
Elderton, Pa
Hey guys. See the pics. I know temp light is #3 on the cluster connector. Seems to be ckt #35 i am not great with these diagrams. Is there a fuse in this light circuit?
No fuse, just the two wires from the dash cluster plug. One that goes right to the temp switch (via the C100/fuse box/forward hanesses connector), the other goes to the ignition switch so the bulbe check can be performed when starting the car.
 

ELCAM

G-Body Guru
Jun 19, 2021
804
93
The number 35 circuit goes out to the temp sender switch and is the ground side of the circuit. The +12V side of the circuit is number 39 the pink and black stripe wire that comes from the 20 Amp "gauges" fuse and that is fed by the number 3 circuit which is one of the fuseable links. Number 3 also feeds part of the ignition switch.

Fuse number 11.

Fuse Block.jpg
 

Baker7888

Master Mechanic
Thread starter
Dec 3, 2021
392
28
Maine
Thanks guys. Ive located the dark green wire under hood (tied back from engine swap) which if im not mistaken went to the old temp switch. I have continuity from this wire to the #3 pin on gauge cluster connector.

What i want to do is have the temp light come on when my elec fans are running.

So to do this would I tie the dark green wire to positive lead of one of the fans?

I have each fan wired to a relay which share a single wire temp switch in the neighborhood of 220 on 185 off
 

ELCAM

G-Body Guru
Jun 19, 2021
804
93
What switches on the relays for the fan?

I remember discussing the +12V power source with you.

You would put the green wire with the ground that is switched on by to the temperature switch that energizes the coil on the relay. So 85 or 86 goes to the +12V from the old electric choke circuit and the other one of the 85 or 86 would go to a temperature switch providing the ground. That is the one you want to connect to the green wire to.
 
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pagrunt

Geezer
Sep 14, 2014
8,228
113
Elderton, Pa
Personally I'd keep the temp light as a back up to a gauge. If you need to have an on light for the fans just use a small LED mounted in the dash cluster face plate.
 
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Baker7888

Master Mechanic
Thread starter
Dec 3, 2021
392
28
Maine
What switches on the relays for the fan?

I remember discussing the +12V power source with you.

You would put the green wire with the ground that is switched on by to the temperature switch that energizes the coil on the relay. So 85 or 86 goes to the +12V from the old electric choke circuit and the other one of the 85 or 86 would go to a temperature switch providing the ground. That is the one you want to connect to the green wire to.
+12v power is from an aux fuse block fed from battery. Attached is a pic of this. Also attached is a pic of the wiring instructions for the fans. 85 goes to switched +12v (glad you remembered about the choke circuit because I didn’t!) and 86 goes to temp switch.

I will splice green wire in question to temp switch and see what happens.
 

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Baker7888

Master Mechanic
Thread starter
Dec 3, 2021
392
28
Maine
Personally I'd keep the temp light as a back up to a gauge. If you need to have an on light for the fans just use a small LED mounted in the dash cluster face plate.
That is a good idea as well.

Let me ask you guys this.

I am using an electric gauge with sending unit located in DS head.

My fan temp switch should be in the neighborhood of 220* on 185* off and located in the water pump body, factory location for a 96 LT1

I got the car to 220 on the gauge and fans did not kick on. For fear of overheating I shut it down for the time being.

Question is….i know i should have just waited a little longer. So how hot is too hot? Or in other words how hot is it OK to let it get? Also was thinking maybe there is a temp difference between the head and water pump ??
 

Baker7888

Master Mechanic
Thread starter
Dec 3, 2021
392
28
Maine
That is a good idea as well.

Let me ask you guys this.

I am using an electric gauge with sending unit located in DS head.

My fan temp switch should be in the neighborhood of 220* on 185* off and located in the water pump body, factory location for a 96 LT1

I got the car to 220 on the gauge and fans did not kick on. For fear of overheating I shut it down for the time being.

Question is….i know i should have just waited a little longer. So how hot is too hot? Or in other words how hot is it OK to let it get? Also was thinking maybe there is a temp difference between the head and water pump ??
anyone??
 

ELCAM

G-Body Guru
Jun 19, 2021
804
93
Keep in mind that the pressurized cooling system is like 16 PSI and at sea level water will boil at like 260 degrees at that pressure.

On most newer cars the fan turn on is the same or higher than the 220 degrees you have now and off would be about 200 degrees or higher.

I would want it to turn on sooner than that but that is a personal preference and not based on any engineering.
 
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