Radiator fans aftermarket wiring

99 DEVILE LOVER

MEMBER
1999 CADILLAC DEVILLE
4.6L
V8
2WD
AUTOMATIC
119,000 MILES

So, I have an aftermarket wiring system set up to the radiator fans that came on the car when I bought it and the fans have never worked but once or twice, so the fans aren't bad, but I don't know how the wiring is set up. Does anyone have any suggestions on how to either revert the wiring back to the factory or fix it? And another thing is the guy said the mechanics at the shop he put it in to get the thermostat replaced had to do the aftermarket wiring because it wasn't working being connected to the factory stuff and I'm trying not to ruin my engine with just barely 119,000 miles.

Saturday, May 7th, 2022 AT 8:44 AM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Unfortunately, there would be no way for us to know how this is wired because not only are there many aftermarket options, but they may have not even wired it according to the kit that they installed.

Which may be part of the reason it is not working.

The only thing I can suggest is that we need to use the factory wiring diagram that I attached below and start at the fans and trace the wiring back to where it leads.

https://www.2carpros.com/articles/how-to-check-wiring

Basically, each wire should be leading back to relays, so we need to trace these wires and make sure they are leading there.

Then we need to follow these wires back to the ECM and then lastly the ECM has a cooling fan relay as well.

If you don't have these three relays, then I suspect the issue is the ECM is not turning them on because it can't.

However, most aftermarket kits come with their own temperature sensor which turns them on, so we need to check the temperature sensor as well.

Please take a look at the diagram and let me know what you find. Thanks

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