Replacing Cooling Fan Resistor Wiring

[four0four]

Because of this exact problem I've designed a fan relay that eliminates the need for these resistors - If this isn't an urgent repair, you might hold out for that. Latest prototypes should be here before the weekend, but then I need to spin up manufacture etc etc.

Otherwise, I'd do what Thom said. There's a few ways to go about it, but simplest (without needing to worry about high current wiring) would be to run a small wire between the TS and TF terminals on the fan relay (pull it out and you'll see). Note that if the car is cold/cool and you turn on the AC, the fans won't turn on until the radiator temp comes up too.

[Tom]

Because of this exact problem I've designed a fan relay that eliminates the need for these resistors - If this isn't an urgent repair, you might hold out for that. Latest prototypes should be here before the weekend, but then I need to spin up manufacture etc etc.

Otherwise, I'd do what Thom said. There's a few ways to go about it, but simplest (without needing to worry about high current wiring) would be to run a small wire between the TS and TF terminals on the fan relay (pull it out and you'll see). Note that if the car is cold/cool and you turn on the AC, the fans won't turn on until the radiator temp comes up too.

Always good when folks design products to help with these old cars! Looking forward to seeing your set up! That said, if memory serves, @944TurboS has a true silver rose '88 turbo S, acquired with very low miles -- so he may lean toward originality?

[barnwerks]

I have had good luck making repair splices on these wires inside the cabin. The insulation is typically in good condition just a few inches from inside the rubber boot penetrating the cowl panel. With the glove box removed, there is an accessible area in which to make the splice.

[Darwin]

My wires were completely deteriorated all the way to the central electrics box. I ended up sourcing new terminal ends and made a supplemental harness to run along the main harness. I have all the PNs for the parts that I used and the cost of materials isn't very high. I may even have some spares I could send you so all you would need to do is get wire.

This offer is open to anyone, BTW. Feel free to PM me.

[breilly951]

944TurboS when I did the splicing in of wires for my resistors, I only had to use about 10" of the new wire, all of which was inside the car. If you are trying to keep it original, I found correct color-coded wires at Rhode Island Wiring Service, Inc (WWW.riwire.com) and got the AWG 12 as Tom recommended. All working fine so far.

[944TurboS]

Thank you! I got the wired and was lucky that I found reasonably good wire when I peek the boot back as far as I could. I soldered the new wires on and hope that will hold for a bit. I do appreciate your input!!

[Schrockahasi]

My wires were completely deteriorated all the way to the central electrics box. I ended up sourcing new terminal ends and made a supplemental harness to run along the main harness. I have all the PNs for the parts that I used and the cost of materials isn't very high. I may even have some spares I could send you so all you would need to do is get wire.

This offer is open to anyone, BTW. Feel free to PM me.

My wires also are bare all the way back to the fuse box. (They end up under the Cooling Fan Relay for anyone trying to trace them back like I did and it took hours to do that. )
I might have to splice the last couple inches away from the bottom of the Fusebox (87 944S) but I like the idea of putting fresh AWG 12 Wires all the way to the Resistors.

Can you give us an idea where you got the terminal ends or numbers. I didn't see how to PM you.

[blueline]

My wires were completely deteriorated all the way to the central electrics box. I ended up sourcing new terminal ends and made a supplemental harness to run along the main harness. I have all the PNs for the parts that I used and the cost of materials isn't very high. I may even have some spares I could send you so all you would need to do is get wire.

This offer is open to anyone, BTW. Feel free to PM me.

My wires also are bare all the way back to the fuse box. (They end up under the Cooling Fan Relay for anyone trying to trace them back like I did and it took hours to do that. )
I might have to splice the last couple inches away from the bottom of the Fusebox (87 944S) but I like the idea of putting fresh AWG 12 Wires all the way to the Resistors.

Can you give us an idea where you got the terminal ends or numbers. I didn't see how to PM you.

You can PM now that you've made your first post.

[Darwin]

My wires were completely deteriorated all the way to the central electrics box. I ended up sourcing new terminal ends and made a supplemental harness to run along the main harness. I have all the PNs for the parts that I used and the cost of materials isn't very high. I may even have some spares I could send you so all you would need to do is get wire.

This offer is open to anyone, BTW. Feel free to PM me.

My wires also are bare all the way back to the fuse box. (They end up under the Cooling Fan Relay for anyone trying to trace them back like I did and it took hours to do that. )
I might have to splice the last couple inches away from the bottom of the Fusebox (87 944S) but I like the idea of putting fresh AWG 12 Wires all the way to the Resistors.

Can you give us an idea where you got the terminal ends or numbers. I didn't see how to PM you.

This is what I used. The only thing I'm not 100% sure on is the connector that plugs into the central electrics box:

M22759/16-12-0 - 12 AWG Tefzel wire/Black (x1 run)
M22759/16-12-2 - 12 AWG Tefzel wire/Red (x3 runs)
160917-2 - Connector at resistors
928966-1 - Central Electrics connector (I had some on hand already from Aaron so I didn't actually buy these. This is what I figured was closest based on PET info)

Wire runs were ~68" but would be good to double check. I couldn't find striped wire anywhere in 12 AWG so I striped mine myself with paint pens. End result was meh but it worked. I really wanted factory colored wire...hence the single run of black and triple run of red.

I made the harness "suplemental" and ran it along the main interior harness. That worked extremely well. I wrapped it in Tessa 51036 harness tape.

Search connector PNs on TE Connectivity.

[Schrockahasi]

Follow up question. When you removed the connectors at the fuse box did you have to loosen the box, pull it up and do it from the engine bay side or from underneath the dash. Access is cluttered under the dash.
Also how do the old terminals come out? Do you have to put a thin flat screw driver blade or terminal remove to get it out or did you have another method?
I guess the 12 awg wire is best. I did some Ai checking and it calculated 14 awg high temp for 25 amp fuse but I’ll go with 12.
I’m actually surprised rennbay or Lindsay hasn’t made kits for this as common as it is.