dannyvera778

iTrader: (5)

Well my fans don't work and this is the code that comes up...tried to see if anyone has a troubleshoot guide to fix this problem...I tried shbox but nothing specific...but they say if this code is thrown more fuel will be used than necessary? Any help please?

vetteoz

iTrader: (13)

Code 77-
Cooling fan control relay circuit.
Check relay circuit for open or shorts to ground.
If no wiring problems are found, replace relay.
Be careful as intermittent short or open can only be detected by wiggling the wires and observing any voltage fluctuations to the affected circuit.

dannyvera778

iTrader: (5)

That's th one I find..problem is that this is a new harness and when I connected the fans it worked then slowly just stopped working hasn't worked since could this be a PCM issue..because I have teste the fan relays and they work fine..is there a relay inside the PCM? For the fans?

vetteoz

iTrader: (13)

factory or aftermarket?

All solid state electronics.
The PCM either grounds the relay control wire or sends power to it to operate the fan

But did you test the relay control wire at the PCM?
As noted above ,
DTC 77 shows the PCM is seeing a fault with the wiring to the relay
If the wire is not making a circuit to the PCM then it can not do anything

89rs454

So if the fans are not hooked up to the pcm it will make it burn rich? I ask this because i Have my fans hooked up to a toggle. **** so do i have to hook these up? TBH This LT runs harder in my 89 then it did in my 95 Formula so i don't know if i believe that. And mine is not throwing any codes doing so.

89rs454

I guess i will be doing my fans up to the pcm just in case lol, but i don't think it matters. My car don't throw any codes and it don't run rich but jic.

vetteoz

iTrader: (13)

Depending what PCM you have you will get a error code if the fans operate without PCM turning them on.

Not a LT1 programming expert but maybe if the PCM tries to turn fans on and it can't
then it richens engine up?

89rs454

Well that scares me now, my car runs great without the fans hooked up. I will hook up the fans and see if i can tell a deference.

89rs454

Your probably wondering why i have my fans unhooked and it was just temp. I was so happy everything worked that i really just left it that way to not **** anything up i was so happy.

89rs454

By any chance can you have this tuned out?

89rs454

Mine is tuned out lol.

dannyvera778

iTrader: (5)

I know the temp which the fans turn on can be adjusted but that's a good question...
This is a Painless harness..

dannyvera778

iTrader: (5)

I know the temp which the fans turn on can be adjusted but that's a good question...
This is a Painless harness..

vetteoz

iTrader: (13)

No idea why you would want to run only a manual fan
but if you set the fan ON temp high enough in the tune ,
then the PCM would not try to turn fan on and therefore would not throw a code when it couldn't do it