Ok I have read many most and seen many diagrams to how a dual fan setup should be. I can not figure mine out hope someone can help me. I have both relays up front behind the battery and both connected to the fan harness. My question is that I can not find the wire that is to go on the block to the fan temp switch traced all wires back to ecm. When I got the car both relays spliced together with the green wire but this keeps them on all the time and it I disconnect only one fan works. Not really seeing on how to get back to factory setting. Please help! Will post some photos later... Everything I have seen has been no help its just the one wire I can not find

 

Sounds like you're all good on the primary fan on the driver's side.

The secondary fan on the passenger's side will come on only under one of the following conditions:

1) ECM commands it on.
2) temp sensor in pass side head reads temp above 238* F.
3) A/C hi side pressure is above 233 PSI.

In either case, ground is applied to the green/white wire on the secondary relay and the fan will come on.

 

For 87, the 2nd fan is not ecm controlled nor runs with a/c. Fan switch is the only link to the fan.

 

My bad. I was just working on the fans on a 1988 this week.

The 1987 aux fan is even simpler in that case. All the OP needs to do is run a wire from the temp switch in the pass side head that will send ground to the secondary relay when it gets to the right temp.

 

So what wire on the secondary relay would I tap into for ground to a temp switch? Thank you for all the great info nice to know!

 

here is what the wiring looks like...still need help please

 

heres one more photo

 

AJ, I also have an 87 ROC and i had a similar set up only worse. I have a 327 block with all the wiring ripped out for the TPI. I had drivers side fan only that would run all the time. I tried to wire back to factory as well and had a hell of a time trying to trace wires. I installed a sensor in the block for the fan to cycle on temp but could never figure out which wire's to use despite all the diagrams i have. What i did temporarily is wired one fan to come on when engine is started and put the a/c or right side fan on a switch under dash. Before i did that my engine water temp would always be 245+ closer to 260 with a 180 deg stat, since i have both fans running i am still in the 245 range but i live in Florida where the temp is 90+. I would be very interested in knowing what you find out so i can solve my problem as well.

 

Kingzrt, I am not sure the ecm is doing anything as far as controlling the fans. I think what I may try is connecting the green and white wires on both relays and run them to th fan switch so when gets up too high in temp both fans will kick on the same time and one is not running all the time. Will let you know what I find out....I guess the 87 is different on the dual fan set up. Would like to know the correct way if anyone knows

 

Did you end up solving this problem? I'm going through it now (I had NO relays). I got one from a donor car and am looking over schematics to figure out the second one. My question: In photo 3, what does that plug do; is it the second relay, or, is the second relay the same as the first?

 

@Majobis Yes second relay is the same...mine is a hack job too! I think I got it down just a real mess. Not sure wich wire you are talking about on third photo. The purple wire that is going into the orange wire is power right from battery. The purple wire is a new connector can not remember what the original color was. So it works I get the passenger side to turn on then when gets to temp turns on other fan.

 

Between obtaining a donor harness and schematic reading help this weekend, here's the breakdown of wire colors for our 87.

The orange goes to the fused wire attached to the positive battery cable and therefore is the main source of power. The tan/white wires are ignition sourced. The green/white wires pertain to the secondary fans/fan switch operation. The black/red sends juice to the fans.

Your photo shows both male and female connectors for the secondary harness wires. Unfortunately, I only have the male and couldn't locate a match, so I'm going to have to do the junction box option.

The tan/white wires also affect the plug going into the back of the alternator (I'm also having charging problems) so hopefully this rewiring project gets wrapped up this week. If I am successful, I'll post photos since this seems to be a problem limited to this specific year.

 

Hello I have a 1989 camaro RS 305 5.0 engine the fan was hot wire to a switch under near the driver side fuse box to activate fan just have to keep an eye on the temp gage. I will like to hook it back to factory spec, Do any on have a sample chart on how to do this and what else to check for to get the fan to come on normally.