today I found my engine temp sensor disconnnected, so I grounded the lead and followed the clicking sound to here:


It has 4 wires coming out of the connector, one of the them was jumped back into the connector, I pulled the jumped wire out and my fan stopped, so I assume it is the engine temp sensor relay?


I reconnected the temp sensor, and let the motor warm up, everything operates like I think it should the fan comes on at about 220* until it cools then shuts off.. it actaully runs MUCH better now.

SO my question is, where's that 4th wire supposed to be connected.

Thanks for all your help, I never would have made it this far without this site!


Chris

 

Just like every relay.

2 12v sorces
2 grounds

1 gound is for the trigger, when it grounds, it grounds out the other.

the trigger ground in this case, is the sensor, there is a 12v that is on that same side of the relay.

the 2nd set, contains a 12v, and then a connection to the fan. once the connetion is opened (triggered by the sensor) it trys to ground, in this case going thru the fan, causing to run.

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I hope that made sense, I'm pretty tired. I'll re-read it after I have gotten some sleep.

 

Looks like someone didn't drive the Audi home tonight?

 

The Audi has been in the garage for a couple of weeks now. I blew a head gasket on it. Waiting to get the Cyl. Head home from the machine shop.

 

Not TBI related.....moved

 

It is the fan relay. One side of the coil has ignition voltage on it, and the temp sensor and/or the ECM grounds the other side; when that happens, the contacts in the relay close, and send battery to the electric fan.

Too bad somebody sodomized the wires to it. I don't understand that. It's so easy to do wiring right (which mostly consists of leaving it alone); I can't figure out why people just have to hack their wiring like that.

 

So the now loose wire is a simple ground correct?

 

Hard to tell...

You should have 4 wires at the relay, IIRC; pink/black small, dark green small, red large, black large. Pink/black = ignition to the coil; dark green small = other side of relay coil to ECM driver & fan switch. Red large = incoming hig-current hard battery; black large = output to fan motor.

No wires direct to ground that I can recall.

I'm thinking that one hacked-off and twisted up one is supposed to be the power to the fan motor, but it's hard to tell.

This is why it's usually better to leave the wiring alone.