81 Caddy rad fan problem

[dieselherb1]

I have a wiring problem with my caddy. Rad fan will come on if wired to battery, but if I connect the two wires at the sensor on the Rad. nothing. Is there a relay or a fuse? I didn't see one.

[maxfax]

What year/model do you have??   I believe there is a fuse for the fan..     An easy check of the relay would be to jump pins 87 and 30 in the fuse box and see if it runs...

[Possum79]

another question is does it have AC?  my rabbit has AC and there is another relay in there so if you turn the AC on it will kick the radiator fan on.

Im trying to understand a little bit better. Basically if you jump the terminals of the sensor it doesnt turn on?

[dieselherb1]

AS the title says 1981 Caddy(pickup) 1.6 no A/C but some wiring for A/C idle control, but no evidence of A/C in the truck(heater control only,no extra holes in firewall) Yes connect the Rad sensor wires together nothing, wire Rad fan to battery, works.

[maxfax]

Duh..   Damn pubpic school education..  Some day I will learn to read..

Hopefully this will be of some help


The #1 fuse is labeled as fan motor..  May wanna check for power there..   THe green arrows point to the fan relay socket..  WIth those pins jumped the fan should run regardless..  THat bypasses the relay and temp switch... If it doesn't run it's wiring somewhere, you may want to inspect the fuse panel itself as these are known to take a poo from time to time.. I think it's pin 30 is hot all the time, and 87 is to the fan..

[Baron VonZeppelin]

I have the same issue with my 81 Truck.
It has A/C.

but .......

Believe mine has had a fuse box upgrade.
It has the blade type fuses.

Was told after i bought it - by a friend - it would have the old style fuses. That was couple/few months ago. I just started fiddling with the Truck and notice it has the newer style fuses.

This diagram looks like it was probably the old style fuses - you got anything like this for me Maxfax ? Maybe 82-83'ish ?

Also - the A/C comp puts drag on the engine when in one of those selections on control panel - and rad fan No Go in that situation either.

[maxfax]

Barron, you're truck should have the blade style fuses..   The oldest MK1 I've had (1980) used them...  That diagram is actually for an '82 Caddy (alldata doesn;t go back before that)..  I believe the '81 should be the same...

[Baron VonZeppelin]

And of course you're exactly right on that Max.
My fuse box is just like that schematic.
Maybe Herb and I can work this thread together without confusing everybody.

The young guru that told me that about the fuses must already be getting rusty on mk1'ism. Don't think he's had one in a while either though, in his defense.

Glad the fuse box is not a replacement. Because the Truck has a couple/few electrical quirks that i was ready to blame on whoever swapped it out. I'll probably do another thread on those things later after i get a little deeper into it.

It was almost about dark today by the time i went to fool with it a little. So didn't do much.
Pulled ALL the fuses and relays out one by one and put them back in to get fresh 'bites' on their connections.
No blown fuses.

The temp gauge started working again after that.
It had been working all along previously - until i took it for maiden voyage. It decided to take a few days off or something i guess.

Last week one of the terminals broke off of the plug-in and stayed on the fan first time i removed it. Or maybe was already like that. I wasn't real sure i liked the way the plug condition looked inside anyhow. Suspicious - somewhat. Spliced on some spade terminals but been leaving wires unplugged from fan.

Have only driven it once since working on it and getting it to run good. Don't want to burn it up now over some fan wiring or problem fan. So been leaving fan unhooked as precaution.

After driving it some for the first time this past Friday and getting it up to what was definitely operating temp real good (since gauge was on vacation) - pulled over in a parking lot and let it sit running - then plugged up the fan wires.
It never budged even a fraction. Let it idle some more to get hotter to be sure - still nothing.

Was going to do as you suggested above - this evening, but started back from scratch with jumper wires to the fan first to double reconfirm which way wires went for correct fan rotation direction.

Reconfirmed proper +/- and marked them, then let fan run about 20 seconds with the jumpers. Had just been doing momentary checks before just to see if it worked at all.
Fan runs pretty damn fast - about like an mk2 on high speed.
is that "normal" for mk1 ?

The alligator clip ends were very very very hot on one of the jumpers when removed - so just stopped right there.

Is this fan a potential problem you think ?
Not in that it isn't coming on automatically - i know thats in the plumbing before it reaches the fan.
But in the fact of how fast it runs, and the jumper getting so hot ? Just want some familiar opinions.

I don't want to troubleshoot the auto function with a fan that might melt my infrastructure/wires or catch my dang truck on fire. Really like the Truck, but I don't trust this mk1 stuff yet.

I can make some heavier gauge jumpers and try it again.
These aren't weaklings, but not quite the same gauge as the fan wires either. They have never presented this condition testing mk2 fans on both speeds.

Can also test the fan on the dead 82 Truck to see how/if that fan runs. Both of those things might be a couple/few more days away though. So just wanted to run that all by you for now.

Thanks

[maxfax]

The fan's on my MK1's sound like air planes..        And they do draw a fair amount of current, not sure exactly how much off hand..  It is route through that 30 amp fuse though..   I suspect they are about the same as the 2 speed fans on high..  WIth the A/C I guess it wouldn';t need to be running as fast till things got warm...

[Baron VonZeppelin]

Thanks Max.
This fan sounded about like an airplane too - good description btw. So its probably doing around normal then ...

IF it operates by jumping the relay slots - yet still will not operate when an A/C related option is selected on HVAC controls - is that going to mean the relay is potentially suspect ?

I've never been much on electricals.

A different friend told me there is a "ground block" up under the dash nearby fuse box that i need to look for and clean all connections hooked to it. I'll hunt for it too.

no rad fan

no fuel gauge (stays on empty side)

no driver side brake light - park mode works - turn sig works.
Bulb goes dead when brake applied with park lights on.
When park lights NOT on - applying brake will activate the lesser illuminous element of the bulb (park light). lol

pass tail light does everything right.
other than no reverse lights - on either side.
not going there for a while.

[mk2diesel]

mk1  fan ..... power from battery +  to rad temp switch out of switch to fan ( red )  thru fan and out on brown to ground.     Pull connector off rad switch and jumper the 2 wires .. fan should run ... if not , then jumper brown wire at fan to ground... still not working? then the wire from the battery + to the rad switch is broken.

if the jumpers work , and the fan doesn't come on when connected in regular fashion , the rad thermo switch is toast.


slower speed ( second speed ) for fan ... go to junkyard (or parts store ) and get a resistor for a FORD taurus/sable rad fan ... (2 wire resistor mounted on the tranny behind the fan)   tie one end of the new resistor to the red wire on your rad fan ... the other gets wired to the fuse box  X relay ( power after start )   almost any size wire can be used, the resistor limits the power to the fan and slows it down .. if the rad gets hot enough, the original rad switch will power  up the rad fan to full speed.

[jtanguay]

if you can't find a resistor this one might work.  its a 100 watt 15VDC one. price is reasonable too considering VW charges about $30-40 for theirs...

[dieselherb1]

I checked my wiring, #1 fuse was blown. But no fan when wires at Rad. switch are connected. But I can hear something in the dash clinking. I took the relay from another truck that the fan does work, still the same clink noise no fan. Haven't checked the brown wire to ground yet. My fuel gauge doesn't work either but I do have power to the power, maybe sending unit or ground. And the horn doesn't work.

[Baron VonZeppelin]

Herb, one of the two rad therm switch wires should have voltage on it at all times - check for that.

Did you try the relay slot jumper trick like Max posted ?

And ... you might be victim to something similar as mine.

------------------------

Got my fan figured out Thursday.
It pissed me off when nothing happened by jumping the relay slots like in Max's diagram - so i got determined. And pretended to be an electrician.

Turned out one of the PO's had rewired the fan system.
Deleting/bypassing all the factory features.
They just put 12volts strait to the rad therm switch.
And it (rad therm switch) evidently is roasted.

Was already aware that a few hack job wiring operations existed under the hood.
I just didn't know the fan was one of them.
And wasn't intending to tackle those things yet.

So dug in and found the right factory wiring they had cut off and tucked back in loom, and some others that were mummified in electrical tape. Got all that stuff out from hiding. Having the virginistic dead 82 nearby as a guide helped A LOT.

Found the right rad therm switch wires - with one having battery voltage. That was good.

Found the right fan motor wires, jumped the relay slots again and got voltage on the positive. Another good.

Removed jumper from slots - set hvac control to A/C - no voltage at positive fan wire - DAMN ! Happened to think, by luck - to turn fan switch on to a speed, and then there was my voltage to the fan wire like i wanted. Had to remember this wasn't an Mk2. lol

So while i was stoked about the diagnostic victory - i tackled the driver side brake light and fixed it too. Then made a temporary dome light (from an Mk2 trunk light) and fixed the driver side door jamb switch. Need to repair passenger door jamb switch too.

I was flat out kikking some azz - i tell ya what.
Almost felt like a real elektrishon.
Then called it a night.

Friday afternoon i got rid of the other spaghetti and unsightly bullshank they had done in past.
Straitened up a bunch of that crap and mapped my plans.
Made a list of needed supplies and went shopping.

Going to hit it hard again this weekend if rain clears out.

[maxfax]

Congradulations Barron!!!      I must just be a lucky sum bugger..   I have yet to have any VWs that have a botched electrical system, or the typical bugs other than a faulty GP relay...