cooling fan inop, broken wiring.

[Joe_Van_Duno]

Hey guys, in need of some help here.

Working on a 87 CSX that is overheating. The cooling fans don't turn on even when the ECT is disconnected (like when setting timing).

I've traced the wires on the relay and there is a white wire that goes to a shared pin. This pin is in the white connector that looks to be part of the transmission harness. The connections go like this

"Top connector"engine side
1 wire goes to cooling fan relay
1 wire goes to ??? (back in loom, not sure)


"bottom connector" transmission side
1 white wire to back up light switch. (assuming, it's on trans and has two wires, one purple and one white)
1 white wire is cut / broken and just hanging.

Also out of the same connector there is another wire, black with white tracer, that is loose. It shares a pin with a big brown wire that is grounded to the transmission.

Can anyone tell me where those wires are supposed to go? I'm not sure if thats the cause of my cooling fan issue, but it sure can't be helping. I've looked on www.oldschoolhotrodder.com and couldn't find the connector in the diagrams he has listed.

[dodgeman87]

Joe,
I'm just checking here. But did you hot wire fan to battery to make sure fan is good ?

[Joe_Van_Duno]

Yeah tested the fan, wiring to the fan, put in new relay, and swapped logic modules. That's when I found a post saying the fan relay is tied into the trans harness at the white wire.

[dodgeman87]

Joe,
I have a '86 service manual with wiring diagrams. I'll be in Plainfield tonight if you need it.

Jim

[Joe_Van_Duno]

Thanks Jim but I just picked up a service manual from brad, along with another harness!! Looks like those wires are suppose to be connected to each other with a diode or something in between

[Oggie Fisher]

I don't have the wiring diagrams you're looking for, but a typical problem is the fusible link for the cooling fan "breaking". There is a lot of information on them on the forum. I would activate the relay and see if you have power at the cooling fan connector. If you don't trace the wire going from the relay to the fan. This happened to me a few years ago.
Rather than replacing with a fusible link you and wire in an in-line fuse.

[Joe_Van_Duno]

Should have update the thread. I put a new starter harness in and the fixed it. The two broken wires were for the cooling fans.

[turbodaytona87]

The starter harness has the cooling fan wires?

[Joe_Van_Duno]

Yeah, if you trace the relay wiring, two wires go into the starter harness (called it transmission harness in original post but was corrected by local member). One wire shares a pin with the backup light switch, and the other gets looped with a diode (or something that looks like a diode) to a ground pin. This car had that loop broken, and the diode fell apart, so I got a new harness installed and all my cooling fan issues were solved.