Radiator fan override switch

[cpttuna]

The other day I attempted to cure my heat soak problem on my 01 by installing a radiator fan override switch. I used the idea of fyrfytr1717 from NAXJA. I have two problems. the CEL and how to get the fan to run with the engine off. I can get it to run with the key on.Iknow Mudderoy might be able to put his $.02 in on this subject. I used the relay and spliced into the dark blue wir with white tracer for power and split the dark blue wire with pink tracer as he did. Comments/suggestions?

[Mudderoy]

The other day I attempted to cure my heat soak problem on my 01 by installing a radiator fan override switch. I used the idea of fyrfytr1717 from NAXJA. I have two problems. the CEL and how to get the fan to run with the engine off. I can get it to run with the key on.Iknow Mudderoy might be able to put his $.02 in on this subject. I used the relay and spliced into the dark blue wir with white tracer for power and split the dark blue wire with pink tracer as he did. Comments/suggestions?

The over ride worked fine for me but I kept having a CEL light. So after thinking about it for a while it dawned on me that I needed a 12v signal all the time, so I ran a line to the battery (really just to test the theory) and it worked! I'm hoping I put this in my original post, because I can't remember exactly what I did now. :( I think I used the 12v from the battery instead of trying to get it from one of the wires in the harness.

[cpttuna]

thanx. I'll give your idea a try when I can get the jeep back from the wife.

[Mudderoy]

thanx. I'll give your idea a try when I can get the jeep back from the wife.

Do you have the aluminum foil around the injectors?

[cpttuna]

yes

[cpttuna]

I had about 10 minutes to work on the jeep after my wife got home from work. Removed the relay and ran the splice(blue wire with pink tracer) to one side of the switch and the other side of the switch to ground. fan will come on but still have the CEL.

[Carves]

I had about 10 minutes to work on the jeep after my wife got home from work. Removed the relay and ran the splice(blue wire with pink tracer) to one side of the switch and the other side of the switch to ground. fan will come on but still have the CEL.


That seems to be a fairly common result with 97+ models.

Luckily, my update model OBD2 thinks its OBD1 and doesnt throw a CEL using that wiring setup ... :D

You will probably be better off just feeding 12v to the fan through another relay ... as per most peoples wiring diagrams for the updates.

[Mudderoy]

http://xjtalk.com/images/special/auxfanbypass.jpg

I'm about 99% sure that all I changed is running the line to the (+) on the battery instead of the Dark Blue / White (DB/WT) line. This way the PCM see's the 12 volts all the time. This fixed my CEL problem.

[4.3LXJ]

That seems to be a fairly common result with 97+ models.

Luckily, my update model OBD2 thinks its OBD1 and doesnt throw a CEL using that wiring setup ... :D

You will probably be better off just feeding 12v to the fan through another relay ... as per most peoples wiring diagrams for the updates.

I agree.

[cpttuna]

thanx. I will have more time this weekend to work on the jeep.

[cpttuna]

UPDATE: As I waited for my wife to get home with the jeep today, I reread all the posts I had printed out. When She came home, I started from the beginning again. The only thing I did different was to replace the Oreilly switch I had initially bought. I had a HD one in the misc parts bin I decided to use. I am using the relay with the darkblue/pink wire split. One side going with the one side of the switch. The blue wire with white tracer is still the ST-Run wire. Bottom line- NO CEL- Maybe time will tell, but al least in the garage no CEL.

[cpttuna]

update(sorry, I thought I had already done this). CEL light came back on the next time I flipped the switch. I took Tony"s advice and wired the relay straight off the battery. I now have no CEL.

[Mudderoy]

update(sorry, I thought I had already done this). CEL light came back on the next time I flipped the switch. I took Tony"s advice and wired the relay straight off the battery. I now have no CEL.

Great to have secondary confirmation!