91 Z28, 350 tpi, auto
Having an issue with my fans not turning on at all, unless supplied directly with 12v. Basically, fans do not operate normally/automatically as they should. I picked up a new coolant temp switch today; but still no change. Still spitting out code 15 (Haynes). Whoever owned the car previously wired the dual fans together. Does anyone have a schematic for this mod? There is a few spliced wires at the relays, but I'm not quite sure how they should be for this. I put the relay wires back to original, still no help. Thinking maybe the ECM is going out? Car has also been sputtering/stalling on me lately. Completely intermittent...

 

go to

https://www.thirdgen.org/forums/cool...-diagrams.html

VERY IMPORTANT FILES!!!

i don't know if they are the right diagrams for your car but they fit 100% my 88 350 tpi!

hope this helps
bye

 

The relays themselves may need to be replaced if in fact you have wired them back up correctly

 

I had the same problem. They replaced the altenator and belt, works perfectly now.

 

Code 15 indicates the ECM is not receiving signal from the coolant temp sensor you replaced. There is an open circuit problem.

The general issue for this would be bad wiring. Someone may (previously) have hacked the wires to the CTS and you are left 'paying the bill'

Bad CTS will easily cause drivability issues as the ECM now has no input to the temp of the motor and cannot trim the fuel to the temp.

For the most part, it will run pig rich and like crap (ie: black smoke and horrid throttle response)

 

I have the same car, with the same engine and the same problem. Make sure you have continuity on the green/white wire from the sensor(front of intake manifold) to the ecu(green plug E16 IIRC). Also make sure you have continuity from the black wire to the ECU(small black plug B8?) Also make sure either one is grounded to the frame/engine. I replaced my sensor and it solved nothing. I replaced the ECU and now it turns on fine albeit at a higher indicated temp.

 

First, thanks for all the replies. Finally had a chance to do some troubleshooting today.

Pin 'E' has proper ground and 12 V.

With pins 'A' & 'E' jumpered, fans turn on.

20 amp fuse under the dash is still good.

Side note: With my A/C on, the alternator does not charge the battery.

Hopefully it stops raining here tomorrow so I can mess with it some more.

Thanks again for the help guys!

 

I got this schematic from Autozone site; could the fusable link be causing something like this?

What is the proper way to test a fusable link and where/what can I replace it with. I've tried reading up on them, but it seems that no one has a definite answer for a replacement; it all seems to be "If you rig this up" kinda deal.