My car has the variable delay feature for the wipers; I believe that was standard on all '81's, as well as the '80's and '82's. If that's correct, then this issue pertains to all of the late C3's. It may also apply to earlier years, but I don't know about that.

It was a little tricky to get this straightened out, but here's the short version. The initial problem was that the power supply wire (brown w/ white stripe) going into the delay controller (mounted in the jack box, behind the passenger seat) had come loose from its soldered connection to the printed circuit board of the controller. However, I didn't notice that upon initial inspection. I had pulled out my official GM '81 Corvette Shop Manual, which indicated two fuses in the fuse block as being necessary for wiper operation. Both fuses (one for the instrument panel, one for the wiper power) checked out OK. I then pulled the motor and checked it, and it was OK.

In the end, I noticed that the fuse indicated in the Shop Manual as the "Wiper fuse" was incorrect. Cross-referencing the Assembly Instruction Manual, I identified 2 errors in the Shop Manual. First, the fuse indicated as the "Wiper fuse" was actually the A/C fuse, and the wiper fuse value was incorrectly indicated as 20A when it should have been 25A.

I replaced the blown Wiper fuse with the correct 25A fuse, and re-soldered the power supply wire onto the controller circuit board, and now my wipers (and washer) work just fine. :D

So, a "heads up" to '80-'82 Corvette owners: First, if your wipers quit working, carefully check the wires from the harness that are soldered onto the controller circuit board. Second, if you have the GM shop manual, go to the section near the end of the book for the wipers, and look for the fuse box diagram; you'll see that the wrong fuse is highlighted, and you'll want to correct the diagram.

Just for a little extra peace of mind, I cleaned that controller module inside and out with electronic contact cleaner (solvent), just to be sure that there were no shorts from any conductive dust that might have gathered on there. That location, in the jack box, is not very clean. There's a drain/vent in the bottom of the box that is open to the underside of the car, and all kinds of dirt can come up through it.

This particular little fix saved me $260 plus shipping - the price of a new controller! :)

 

I have the same problem with my 1980- the wipers work with the exception of delay. In you post you indicated that the wiper fuse was acutally the fuse for the AC. Then what is the proper fuse. I followed the shop manually before putting the car away last fall regarding the problem, and if the fuse showing in the shop maunal was for the ac then which fuse or fuses would repesent the wiper control - ( still waiting for my AIM manual to arrive )

Thanks

 

Looking at the fuse block, the A/C fuse is directly above the Wiper fuse. In between the two, in really small lettering, it says "WIPER". So I'm sure that's where the confusion came from. The A/C fuse is above, the Wiper fuse is below. And BOTH of them should be 25 amp fuses, for the '81 anyway, and probably for the '80 as well.

I just remembered ANOTHER error I found in the shop manual - it references an IN-LINE fuse, that it says is in the instrument panel harness near the fuse block. THERE IS NO IN-LINE FUSE. My back still hurts from laying across the door sill with a flashlight in my mouth, tracing every wire within a foot of that fuse block, looking for that @#$%^! in-line fuse! :mad: If it's there, it's not blown and I couldn't find it! There was no reference anywhere else to an in-line fuse; not in the wiring diagram, not in the AIM.

But if your wipers work on Lo or Hi but not on Delay, then it can't be the fuse, anyway.

Here's what I would check. Make sure the pink wire that goes to the plastic cover of the wiper motor is OK (it's the single wire, not the 3-wire plug). Make sure the 9-wire connector between the harness and the controller in the jack box is clean - spray it liberally with contact cleaner. Also spray clean the printed circuit board of the controller, top and bottom. Inspect the controller for signs of damage or overheating, burned chips, whatever.

There are 2 connectors on the switch that could be loose, broken, or dirty. And, of course, the switch itself could be the problem. There is a tiny screw that goes into the bottom of the switch at an upward angle, attaching the switch to the back of the dashboard. It's nearly impossible to see, but if you can get your head under there and enough light to see past your hand with a small phillips screwdriver, you can get that screw out and drop the switch. Getting the screw back in is 10 times as hard.

Any diagnostics beyond that are beyond me. The shop manual and AIM are no good at all in diagnosing the controller. The shop manual doesn't even have any trouble-shooting for it at all. I guess a GM technician would just start replacing parts until it worked. $$$....

Good luck! :seeya

 

Thanks for the Info I guess I have to go back to the drawing board and try to fix the delay problem with the wiper, funny thing is that the wipers work o neither setting with the exception of the delay function

 

Hi Gator!
I also spent ages looking for that mysterious in-line fuse. Couldn't find it, so I put it down to ignorance (on my part!). There seems to be a few errors in the shop manual - especially regarding the electrics. I found the problem with my wipers quite soon (once I gave up looking for the in-line fuse). The module was just rattling around in the bottom of the compartment!!! Once I plugged it back in (after sticking it back together) everything worked fine. But what a dumb place to put it! Why not have it under the dash near the motor & switch?
:cheers:

 

Ratt7,
If you're better at deciphering wiring schmatics than I am, or if there's some knowledgable help around (that's you, UKPaul! :) ) you might be able to figure out which wire coming out of the switch should be carrying what I would assume to be a varying voltage as the delay rheostat **** is rotated. If you can identify that wire, and you don't get the proper variation as the **** is rotated, then I would think you've identified the switch as the problem. But I'm far from sure of that. The interaction of the controller and the switch is totally bumfuddling to me.

Paul,
You know, my controller was also lying in the bottom of the jack box! That's probably how the soldered connection got broken in the first place. It appeared to have been attached to it's little black plastic housing by nothing more than a piece of tape! :eek: I put it back in the plastic box, and put a nylon zip-tie around it to keep it in there...

later, :seeya

 

In my 82 the contoller was also lying on the floor,it looked like only a piece of tape holded it in his place.I used a plastic zip-tie too to keep it where it belongs.

My wipers worked,but the "mist" and "delay" functions were gone.I have taken the controller out of the car,and used alot of contactspray to clean it.Solved the problem for me! :yesnod: :D

 

The only reason that I found my problem was that I was trying to find what was causing a loud rattling noise (having just changed the exhaust system I had visions of it banging into the fibreglass rear spring, or maybe even the bodywork :eek: )
My controller was also held together with a piece of tape, so I used a plastic zip-tie instead (great minds think alike ;) ). After finding the remnants of the tape I immediately blamed Bubba for it. Now I realise that it was GM that had used tape (maybe trying to reduce sprung weight?), I would like to take this opportunity to publically offer Bubba my sincere & humble apologies :D

 

The older control boxes are the same, except for the color coding of the wires and the connectors. Mine was shot and I picked up an older one and rewired it to accept the 82 harness.. no biggie.

Marck

 

I am finding quite a few errors relating to the electrics in the shop manual. Hopefully I figure out the problem before I have the whole system memorized. :crazy: The ECM is bad, and my battery dies over night sometimes (maybe 1 night every 2 weeks, but is fine the rest of the time)

 

Stickboy,
just a shot in the dark here.... pun intended... :D

A couple of years ago I was going nuts :crazy: trying to figure out why my battery was dying. There was no pattern to it. It would be fine for a week, then one morning: dead. Charge it up, fine for some random number of days, then one morning: dead. wtf? :confused:

Finally, just by chance one night, I happened to look out in the garage to make sure the door was down, and I saw the interior lights come on in the car, all by themselves. It was the !@#$%^! courtesy delay timer! The thing will go nutso, and start turning on the interior lights, leave them on for several hours, maybe all night, then turn them off before you come out and get in the car! Long story made slightly longer... replaced the timer and the problem went away. Part number ES-341, $45 from Zip. :)

This may or may not be your problem, but it's easy enough to check out. If you haven't tried it already, just remove the inner glove box, and look for the orange plastic module, about 2x3 inches, maybe a half inch thick or a little more. Mine was about half melted from the malfunction! Glad I found it before it started a fire... :eek: Anyway, just disconnect it. This will stop your door switches from operating the courtesy lights, but the lights will still work with the headlight switch. If the dead battery problem goes away, then you've found the culprit.

Good luck! :seeya

 

Gator81
I agree with you that the delay rheostat may be at fault here, everything about the wipers is working with the exception of the delay option. I am going to spend a bit of time and try to determine how to approach the issue with the delay rheostat - it likely straight forward but will take a little time to figure out - At least one idea I have is to try and over ride the delay rheostat and see if this works

Thanks

 

Stickboy:
I've fitted one of those battery disconnect things. Each time I leave the car I just unscrew it, stick it in my pocket & go home. I haven't got any worry of the battery going flat overnight & there's the bonus of would be car thieves having a little extra trouble stealing it. The main reason for fitting it is that if anything shorts out while the car is garaged, then the whole thing could go up in flames (along with the house :( ).

 

UKPaul, it is a carryover of the same slop-assed wiring and design/assembly techniques they employed on my '72 probably earlier.....tell you what, Corvette engineering is impressive SOMETIMES and downright STUPID other times...I think the layouts of vette electricals leave a LOT to be desired, and the newer one's are worse....
putting computers in the engine compartment for instance...
putting computers in the BATTERY compartment, plus any other electricals...
super smart....
talk about PLANNED obsolescence....that's it....

GENE

 

Thanks Gator81 and RATT7, I have seen my light on from time to time, I figured it was the door open, so I just opened the door and shut it and the light went off after a few seconds, I will check the module. :cheers:

 

Another thing, the C4 courtesy light timer fits the 80-82 (and maybe earlier) harness! The pinouts are exactly the same, the only difference being that the anchor clip is on the wrong side, just press it in firmly or break off the tab. It'll work just fine and the C4 timers are easier to get a hold of tha the C3 ones.

Marck

 

Gene,
We design stuff that contain microprocessors, RAMs, blah, blah, blah & have to go to great lengths (fans, heatsinks, board layout, etc) to ensure good heat dissipation to get the high MTBF figures needed to be able to sell it. Then GM come along with a box containing the same type of componants.... and slap it in a hot engine bay!!!
Could the strange positioning of things like the wiper module be due to them using an existing wiring harness (earlier Vette, or different car altogether) & doing a few minor mods to it, rather than designing & kitting up to manufacture a completely new harness (ie. componant positioning is dictated by the harness)? Or is it a basic as an engineer saying "Ah, there's a convenient gap - I'll stick this in it"?
:cheers: