jb4xx

Recently purchased low mileage 93 trans am. Temp guage was not working so we changed sensor when doing opti replaced. Temp creaps up to red at lights, got stuck in traffic and had to pull over and turn it off. Going down the road, temp indicates 220. Just flushed coolant several times and have same results.

Fans come on when obd ports are jumped. Fuse is good, tried swapping relays, still no fans with temp all the way to red zone.

What am I missing???

Injuneer

I assume you changed the coolant temp sensor in the head, since you indicate it fixed the gauge. What about the CTS sensor in the water pump for the ECM? Have you scanned the ECM for codes?

jb4xx

No codes when jumped the pins tonight, fans came on when jumper was in.

Changed both sensors, even put old sensor back in water pump and had same results

moparman

It's normal for these cars to heat up when stopped or creeping in traffic. Fans should come on right about the third hash mark. Depending on ambient temp, 220 might not be to high driving down the road.

jb4xx

Turned the car off as it reached the line where the red. Didn't want to damage the engine

Injuneer

I would check the accuracy of the coolant temp sensors:

Courtesy of Shoebox

4th Gen LT1 F-body Tech Articles

Do you have access to scanning software that would show the temperature being reported to the ECM, and whether it is commanding the fans on - 1st fan at 226*F, second fan at 235*F?

GaryDoug

Like Fred suggested, get it scanned to see what the PCM sees as engine coolant temp. A bad connection in the wiring to that sensor can make the reading much lower than real and that might never turn on the fans. You can use free TunerProRT and the 93 definition file (da2.ads) to scan the readings, but will need an OBD1 cable.

jb4xx

Anyone in the Louisville ky area have a obd1 scanner?

Saw a usb connection obd1 for $59. Is there a cheaper option?

GaryDoug

$59 is about as low as I have seen. You can make your own for under $20, but you have to order the materials on ebay from China (2 weeks) and it requires a small amount of electrical familiarity, like splicing wires and such. See this topic:
https://www.camaroz28.com/forums/com...95-lt1-874306/

moparman

What part of town are you in?

jb4xx

20 minutes away in Indiana

Work in east end.

moparman

Here's a link to a local board. I know there are some guys in southern Indiana that might be able to help. Join up and ask.

F-Bodies Unlimited Message Board - Powered by vBulletin

jb4xx

My son attends. Diesel tech classes at local high school vocational school. His teacher asked if ac was charged. I thought, it shouldnt matter. I charged the ac until compressor kicked on and fan came on. I turned the ac off and let it idle and sure enough the high speed fan kicks on just as the guage enters the red zone!

The fan stayed on until temps were half way between the 220 and red zone

I'm thinking about installing different ect to trigger fans at lower temps. Override switch would be last resort. May replace radiator, who knows how much its blocked up. 20 year old radiator with only 56 thousand miles, car sat around a lot the last 10 years.