A/T oil temp warning light

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

May 25, 2005
North Shore
EDIT - This fixed itself - Love it when that happens

So I have this light on my dash, but I know it's not an overheat issue because it is on as soon as I turn the key after the truck has been sitting for ages.

I've searched around a bit and found 2 possible reasons:

A - The charging system/alternator is at fault
B - Sending unit from trans

I'm thinking it's 'B'. How would I test this? Just unplug the sending unit? Anyone had this warning light with their '80 series?

Last edited:
Hey Dorian,

I've gotten this warning light on my 80. However it was during a long up-hill climb so I can only assume it was actually correct. I'd like an actual temp gauge for the trans to see exactly what it's doing. Maybe that would be a worthwhile investment for you at this time? That way you would be 100% certain that the temp light was misbehaving and not just ignore it sometime while it actually IS getting too hot.
The A/T warning light is a light that tells you you've cooked your tranny. By the time it comes on damage has often been done. Get a tranny temp gage! Or at the least, make sure your revs are over 3000 RPM when climbing long hills. 3000 is the magic number; above this the torque converter won't cook, below that it will heat up rapidly. I know from long experience watching my tranny temp gage while climbing the Duffy.
Tranny is working great: no weird smells, shifts are smooth and firm and the fluid is still gold.

I'm with Safari, I think it's a short somewhere, charging seems good, lights aren't dim or anything. I will try a used sender, but when I unplugged it the warning stayed on :confused:

Yes it's a popular upgrade to tap into the tee at the sender and put a gauge in.

thanks for the feedback
I had my trans temp gauge before the cooler and I used to see rising temps on slow hill climbs and rapidly rising temps on the dry lake bed at Black Rock Desert. Now with the cooler installed, the gauge never moves. Never had an idiot light on btw. Cooler is cheap insurance. I had custom metal brackets made, didn't strap it to the rad. Used the cooler for the 24,000 gvw truck.
That otta do it :)

Users who are viewing this thread

Top Bottom