KingpenM3

I have finally gotten around to tracking down what is drawing my battery down (1979 L82). I hooked up a test light and had a sure enough "medium" light of draw with all of the doors closed and everything off. After checking a few things I disconnected the test light to hear the loud click of a relay, but I couldn't tell where in the world it was. I finally tracked it down to under the gear selector, and even then I got the side wrong until I found it was this one on the drivers side underneath the gear selector.



Unplug, and the draw is gone. The relay activates if the car has power every time. After some googleing, it seems that this is a wiper relay. What does it mean that my relay, and connector only has 4 connections? It seems that all of the relay replacements that I can find online have 5 connectors?? Does this mean I do not have intermittent wipers?

So where do I go from here? All I know so far is that the relay is functioning. Even though I'd love nothing more than to swap a relay and be done. I did move the wiper switch to all of the positions and the relay responded the same in all positions. I guess I could unplug the wiper switch and see if the relay still draws? Thanks for any help!

SwampeastMike

That's the alarm relay. Many aren't even aware that most C3s came with a standard factory alarm.

The problem with the '78+ alarm system is the extremely finicky arm/disarm switch installed on the driver side door key lock. That switch very frequently fails or sticks in the closed position causing the alarm horn (it's mounted on the firewall behind the brake booster) to sound constantly. Many simply disconnect (or rip out) the wires to the horn and think everything is OK. Nope. The alarm relay will still be energized and drain the battery.

You can try unlocking the driver door with the key to see if the relay deactivates. Since your horn is dead, disconnected or removed however you might as well just remove the connector at the relay. Your problem will be gone. If you want to get the alarm system working you'll need to address the horn as well as the arm/disarm switch. (There is also a tamper switch installed on the key lock but unless it literally falls off--unlikely--it doesn't tend to fail.

Presuming you have intermittent wipers there is a module that includes a relay. It's installed further forward in the center console and has two electrical connectors containing quite a number of wires.

KingpenM3

Awesome! I had read a bit last night about the alarm relay, but I guess when I saw a relay that looked like what I was looking at I figured it was the wiper relay.

I believe this will also explain the wire that I found dangling around the drivers side firewall aread of the engine bay, probably the wires to the alarm horn.

Thanks so much. I'll just leave it disconnected. Cheapest fix I've found on this car so far!

SwampeastMike

There are two wires leading to the horn, one orange and one yellow. They yellow one is -12V (ground) supplied by the alarm relay when the system is triggered. The orange is +12V constant power direct from the CTSY fuse. If the orange wire has been disconnected be certain it is taped off!

KingpenM3

Quick question. What is the correct operation of the wiper switch? Is it:

High
Low
Off
Pulse (turning **** changes pulse speed)

I have never used them, but when i was messing around with everything chasing the draw i left them on (a pretty painful process to watch them trying to run). Now i just want them back off. Thanks!

SwampeastMike

From top switch position to bottom:

High
Low
Intermittent (**** changes speed)
Off
Single sweep (momentary contacts)

KingpenM3

Thanks!

SwampeastMike

It sounds like you're having some problem with the wipers.

Most, but not all, '79s had interval wipers. Beyond the special switch (there should be an arrow indicating "turn" on the operating button/lever) there is a delay module installed ahead of the shifter and a special cover on the wiper motor. Look for a single pink wire coming out of the plastic wiper motor cover. If the wire isn't there the interval feature will not work as it leads to a contact that closes for a few degrees of each full rotation.

My original '79 interval module still works fine but it is known as a fairly common failure item. My wiper motor cover was missing and I was VERY lucky to find a replacement at a reasonable price--they are no longer available new from any source and originals can be difficult to find. Refurbished and working original interval modules are available from the vendors but are rather expensive. A failed module that causes problems with the wipers in any mode can be bypassed. Inexpensive kits are available for such but it's not difficult to DIY without cutting any factory wiring.