Conway

This is on my daily driver, an 83 GSL. For some strange reason after turning my wipers on yesterday they won't turn off. I've already spent two angry hours with my little multimeter and my shop manual trying to figure out what is wrong. And I just did a couple of searches, but found nothing pertaining to me. Here is what I know:

The wiper motor is functioning properly, but is receiving 12v to its slow speed connections all the time.

The wiper switch is functioning properly.

Disconnecting the "CPU" does not make the wipers stop. Neither does disconnecting the ground at the wiper motor.

So, Anyone have any idea on what I should check? Thanks,

Conway

Pedestrian X

sorry i cant help ya but thta is sorta funny hehe

Conway

Ok, well, I'm an idiot. Turns out the CPU is the black funny-lookin thing, not the silvery useless thing. (Still pretty useless though) Anyway, turns out the CPU is the problem and I'm tryin to figure out what to do about it. Thanks anyway,

Conway

Pedestrian X

No problem bro :] and good luck.

82transam

iTrader: (18)

i think the silver thing is the emissions computer isn't it? As for the CPU, just find another one in a junkyard and put it in, i doubt you can repair those things.

ricola555

Wipers running all the time? Have you considered moving to a wetter climate such as a rainforest?

Conway

Yeah, no dice on mending the CPU. Thought I'd try though. Gotta try and find a junkyard 'round here with an 83.

Conway

Anyone know whether or not I can use a CPU from a different year?

Pedestrian X

i knwo and 84-84 onme owuldent work.. i don thtink? mebbe an 81-82 ? i don thtink one fomr an SA woudl be the same either??

MyRxBad

Am I missing something here or are you guys thinking the CPU has something to do with the wipers?

The wiper motor is connected to the battery via the ignition and the wiper switch. There shouldn't be anything to it. Either there is a short in the wires along the path or your wiper switch.

http://www.iluvmyrx7.com/1st_gen_manuals.htm

Download a wire diagram and do some more testing.

Conway

I have a shop manual and the intermittant wiper function on 83 models is controlled by the CPU. Working on a little timer-type circuit, the CPU completes the circuit briefly to start the wipers going and the a switch on the wiper motor takes it from there. My CPU is simply completing the circuit constantly.

Pedestrian X

i guess for a temporary fix you could disconect the wiper motor?

Conway

I just took out the wiper fuse.

MIKE-P-28

iTrader: (1)

That little CPU is only a relay box for the intermiten wipers , or so I thought. Id say the wiper switch has a closed connection and is either stuck or is bad

Conway

That is exactly what the wiper part of the CPU does (the other parts control turn signals, the chime/buzzer and a couple other things). Mine isn't just doing it intermittantly, its doing it all the time, hence wipers won't stop wiping. I'm pretty sure its the CPU, at this point, though, since I've tested the whole circuit outside the CPU (including the wiper switch many times). Thank you everyone for your help. I'll just have to see if a new CPU helps (assuming I can find one).

Conway

BrewerBob

I don't know anything about the CPU but I find it hard to believe the CPU controls the wipers. Maybe the delay between wipes but your CPU isn't doing turn it on and off. Sounds like you have a stuck relay. I timing circuit (for the delay) is going to be a resistor and capacitor (mabye an inductor). The simple electronics of the day were mostly 5 volt stuff.

pratch

The cpu in the 1st gens is extremely simple. It controls things like door chime and yes - intermittent signal for wipers.

*shrug*

Don't ask why - drink Bud Dry!

BrewerBob

Now I definitely don't believe you. Anyone who drinks Bud doesn't know what they are talking about(much less dry).

Yes, I believe it controls the delay between wipes but turning them on and off is going to be a fairly heavy current/voltage spike. Relays don't mind that too much but even a 555 IC timer chip (these were out when I was in high school so they been around long enough) wouldn't last long.

Conway

Maybe I'm wrong, but thats what the manual leads me to believe. I can turn he wipers on and off with a wire bridging the right connections at the "CPU" too. Wipers work fine with the CPU disconnected, just don't do the intermittent thing and won't automatically return to the bottom of the windshield.

Conway

82transam

iTrader: (18)

ok, where is this cpu thing? unless one of my friends stole my parts car's (an 83) it would still be there. Where in NJ are you? if you close, just come get it.

pratch

For the record, I don't drink anything with Bud in it.

Killians is about as close to slumming it as I get


The CPU "thing" is under the passenger-side carpet in the footwell area.