Wiring/trigger issue for cooling fan

DrEntropy

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Now the cooling fan will not come on... have 12V+ at the relay, fan runs when relay terminals are jumpered. Relay is also getting trigger voltage at brown/white lead.

The green/white is apparently the trigger but I can find no wiring diagram. Is there a fuse on THAT side of the circuit? Counter-intuitive, IMHO.

I imagine that G/W wire gets a "ground signal" directly from the ICM?
 
What is the engine temperature, is it around 210/215 or higher, how about when you turn on the A/C?
 
What is the engine temperature, is it around 210/215 or higher, how about when you turn on the A/C?

A/C inop. Watching the gauge, the fan used to come on at about 2/3 to 3/4. No good way to check temp running just now. Two known good relays.

EDIT: I get a 100Ω resistance reading at the G/W wire on the relay plug with engine off.
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The ECM grounds the fan to switch it on.
Lots of folks hot wire it to come on with ignition.
Mine is triggered by the marker lights with the relay grounded to the fender.
 
I MacGyver'd this one with a switched ground to the relay from a manual switch in the cockpit. I may hunt down a thermal switch we can mount on the radiator to make it a bit more "automagic" for the owner.
 
You might want to add a light downstream to let you know that the fan is running ,switches are not allways turned on. ;)

Doug in P.R.:cool:
 
You might want to add a light downstream to let you know that the fan is running ,switches are not allways turned on. ;)

Doug in P.R.:cool:

THAT is the truth! Though this guy is very aware, that may be a good idea.
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Now the cooling fan will not come on... have 12V+ at the relay, fan runs when relay terminals are jumpered. Relay is also getting trigger voltage at brown/white lead.

The green/white is apparently the trigger but I can find no wiring diagram. Is there a fuse on THAT side of the circuit? Counter-intuitive, IMHO.

I imagine that G/W wire gets a "ground signal" directly from the ICM?

That's just how mine was.
 
That's just how mine was.

I like the old sensor style fans from the early 80's , I think the computer in OBD1 fails to send the trigger signal which leads to many a overheated / wasted Sunbird.

OBD2 cooling signal can be changed with a laptop program, OBD1 wasnt too far advanced to even have this ( cooling fan control) built in IMO. ( I dont know why they even attempted it.)

Just engineers thinking too far ahead ( or penny pinchers being lazy ):rolleyes: ( lets save $5 by eliminating the grounding fan sensor and let the computer do it)

Just my .02

Doug in P.R.:cool:
 
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I'll start testing with a snap disc in the spring. Screw the ECM! I want to find something better anyhow.
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