Cooling Fan Issue - Anyone have a wiring map?

[Mad Bull]

Hey, everyone.

I'm having issues with my radiator fan. Bastard doesn't want to turn on. My uncle used to be a mechanic, so he is helping me out. We came across the problem late last night, after we had spent the evening replacing the radiator, thermostat, and removing a broken bolt.

Anyway, I've been reading through the threads regarding the issue, but a lot of the electrical talk is hard to follow. My uncle was saying we could really use a wiring map, and I was wondering if anyone could help me out.

Thanks a lot!

[NavySVO]

First of all, look under the dash, just to the right of the steering column. There is a module for the cooling fan. It should be a black box (probably says BOSCH on it). That is probably your culprit, as it the cause about 95% of the time.
Try for wiring.....just a bit to sift through

http://rothfam.com/svo/reference/

[Mad Bull]

Thanks a lot.

I actually went to Checker last night to replace that box, but I was going to need to go to another location to pick up the part, so I figured I'd wait. I believe my little black box says "TRW". Are we talking about the same thing?

[BrianO]

Thanks a lot.

I actually went to Checker last night to replace that box, but I was going to need to go to another location to pick up the part, so I figured I'd wait. I believe my little black box says "TRW". Are we talking about the same thing?

yep, that's it

[Mad Bull]

Thanks. The wires look good going into that relay, so I'm hoping it's a quick fix. It's the only thing keeping me from getting it on the road, I think.

[BrianO]

while you're there you might as well wire in a manual fan switch and mount it under the dash there somewhere. I got a low cost push/pull switch and used one of the splice connectors and wired it to pin 1 which goes to the sensor on the intake telling the fan to come on, the other wire on the switch to ground. I believe it was a white wire on the TRW module, but can't remember right off..

the fan sensor is set to come on between the A and the L on your gauge..but if you want to keep it cool in traffic before that just reach down and hit the switch. once you get to cruising speed again it will cool off.

good luck

$.02

[NavySVO]

I believe my little black box says "TRW".

TRW...

If you have some extra pocket money, you might want to go with an after market controller like SPAL. All the wiring stays under the hood, and you can use the factory sensor on the engine.
You also program it to have the fan come on half speed at the temperature you select, and full speed at the temperature you select.

[IXLR8SVO]

Forced4 has a Fan Control Unit.

"You can replace it outright or preserve the original TRW casing and just swap in the circuit board"

[Mad Bull]

I may do that eventually, IX, but right now I just want to get my car on the road. I need it for my commute and slow traffic is pretty common. I need the fan to be dependable.

Replaced the single row radiator with a 3 row and also replaced the thermostat. The fan is the last piece of the puzzle.

[BrianO]

I may do that eventually, IX, but right now I just want to get my car on the road. I need it for my commute and slow traffic is pretty common. I need the fan to be dependable.

Replaced the single row radiator with a 3 row and also replaced the thermostat. The fan is the last piece of the puzzle.

same reason I did exactly what you're doing..but the manual switch is a must.

the fan won't come on automatically until the engine is super hot..like 220 or something..it's better to turn it on before it gets that warm.

just my $.02

[Mad Bull]

Guess I'll look into that, then. What does that SPAL system run, NS?

[NavySVO]

Guess I'll look into that, then. What does that SPAL system run, NS?

It's around $100.00 shipped. To some folks $100.00 would be too much to spend when you can get the TRW box for cheaper.......but I see it this way:

1. you take that poor existing wiring out of the equation and keep that amperage draw out of the cabin where it might burn up more than a module.
2. The replacement factory style module will probably go poop again and you had spent that money for not.

"These are just my opinions and do not reflect those of the SVOCA or any of their sponsors or affiliates."

If you go to the SPAL site, look at the PWM controller. To purchase, click on "find a dealer"

http://www.spalusa.com/

[IXLR8SVO]

If you want to try temporary fix until the real deal comes in, give these two ideas a try:

Plan A:
Before messing with the wiring, give this (cheap) trick a try that should give you manual control of your cooling fan from your existing dashboard heater control:

The AC compressor clutch shares the same circuit as the cooling fan and should over ride the fan control when you turn on your AC. Pull the plug off of the AC compressor and stow it back in a safe place so it doesn’t get caught up in anything. Then, when turn your AC on or off at the dash, this would over ride the fan control and kick on the cooling fan.

Note: If your AC is low on coolant, you might need to put a temporary jumper at the dryer. There should be a 2 wire plug located on the dryer (engine compartment/pass side) that is called the “Clutch Pressure Cycling Switch’ that will protect the AC compressor if the coolant gets below 23 psi. Pull this plug and put a jumper across it if the fan does not kick on.


Plan B:
At the TRW box, put a temporary jumper wire between pins 2 (Orange w/Black stripe wire) and pin 5 (Brown w/yellow stripe wire). If the fan kicks in, your in business.
Make up a temporary jumper with a toggle switch and you should have manual control of your fan.

Here is a copy of the cooling fan schematic from the Mothership

[Mad Bull]

IX, thanks a lot. I'll see about plan B. All the under-the-hood hardware for my A/C was removed by a PO. Do you guys think this could be affecting my fan's performance?

[IXLR8SVO]

Bull,
PM me if you want an easier to read (larger) schematic. I had to reduce mine down for the post and its not easy to read