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FB wipers won't turn off

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Old 11-06-18, 07:47 PM
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FB wipers won't turn off

I have a 1983 RX-7 LE that's developed a weird problem, the windshield wipers won't turn off.

This started happening just a week or two ago, before that they worked fine.

They work correctly on low speed and high speed but when you switch to intermittent speed or turn them off they keep operating at low speed.

I have to pull the fuse to turn them off when not needed.

I switched out the column switch cluster with a newer one to fix a different problem I was having with the high beams (they weren't turning on).

But the new column cluster didn't make a difference with the wiper problem so apparently it's not the column switch for the wipers itself.

I also cleaned up all the connections from the wiring harness to the wiper assembly itself but again, no change.

I'm out of ideas, can anybody make some suggestions?

Thanks!
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Old 11-06-18, 10:03 PM
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The most likely culprit I'd say is the wiper "computer". It's a relay looking thing mounted in a black enclosure under the dash near the steering column. I believe it uses a 6-pin block connector and is mounted via a single 10mm nut. I lost my park and intermittent feature just about a month ago and I took the computer apart, cleaned it and it's contacts, re-soldered the contacts, and reassembled. This fixed my issue, although if it hadn't, the other possibility would have been the motor itself. There is some contact bit inside the motor (it's been a while since I rebuilt mine so I'm just grabbing at air here) that tells it where to stop spinning. If this has failed or become corroded, that could cause your wipers to not stop. Try this: run your wipers on low and then switch to off while in mid sweep (before or after direction change, but not too close to the resting position). If there is a slight change in speed, that would indicate that the park function has been activated. This would mean the computer is "looking" for the signal from the contacts in the motor to shut off the wipers at the right spot. There may not be a noticeable change in speed while doing this, but if there is, at least it let's you know part of the system is working. If a change in speed is noted, there's a higher chance that something in the motor or wiper wiring is the issue rather than the computer. Regardless, start with inspecting and cleaning the computer, it's the easiest fix if it's the issue. I might have some pictures of the motor internals somewhere. If I find them I'll be sure to post them.

Edit: Take all of this with a grain of salt. Like I said, it's been a little while since I did the work on my car so... Hopefully some others can validate what I've said here.

Last edited by Benjamin4456; 11-06-18 at 10:08 PM.
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Old 11-07-18, 02:35 PM
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Thanks for the golden nugget Benjamin, I think you have given me the information I need to solve the problem.

You've identified the "black boxes" I needed to know about, the one under the dash and the wiper motor itself.

Fortunately I have an 83 GSL parts car I can "borrow" these parts from if I need to.

It's a nice day here in Georgia, sunny 72 degrees, so I'm going to take your instructions and go out and see what happens.

Thanks!
Ray
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Old 11-07-18, 11:57 PM
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I'd take a look in the motor. There is an "off" spot inside the motor itself. If it has grounded out or somehow malfunctioned it could cause draw and a "rampant wiper" situation.
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Old 11-08-18, 10:52 AM
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It could be a ground inside the switch or at the motor. Maybe the connector plastic has disintegrated under the panel. Doesn't hurt to check.
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Old 11-08-18, 12:59 PM
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You are right about the connector plastic under the panel Jeff, it was crumbling on both the male and female ends.

I was hopeful, but it turns out that wasn't the problem.

I carefully cleaned and redid all the connections, using electrical tape to replace the missing plastic connector parts, but no change.

With three votes now for the motor I think the smart money is on replacing the entire motor and transmission assembly with one of the spares that I have.

If that doesn't fix it I guess I'll have to start digging under the dash according to Benjamin's procedure to find that little black box that's the Wiper Brain.

I took a quick look the other day and was reminded of how much I hate digging under the dash, then it started raining.

Looking good today though, I'll see if I can get that new wiper unit in and see what happens.

Thanks Guys! And it's great to hear from Jeff20B and James!
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Old 11-08-18, 01:56 PM
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If you've got another wiper assembly around, by all means set it on something so the arms won't knock it off or damage the car, and hook it up to the connector in the cowl. If that fixes it, voila solution found! If not, ya just saved yourself a painful wiper assembly removal (for the time being at least). Not sure if there's some trick to it, but getting the wiper linkages and motor out of my 7's was one of the most annoying things I've done to date.

While you've got the assembly out, I'd go ahead and disassemble the linkages and lubricate/clean them. The pins that the wipers attach to have a tendency to freeze up over the years, so might as well do some preventative maintenance while it's easy to get to (unless of course you have a very well kept or new unit). Use a good grease that will stick around, not just some WD.

And yes, these wiper connectors seem like they always fall apart - mine is held together with electrical tape too . I'd like to see if there's any first gen out there that's been driven often and doesn't have a disintegrated plug.

Best of luck with finding the issue.
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Old 11-08-18, 02:55 PM
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Thanks for the heads up Benjamin, plug and play is the way to go on this problem.

This solution actually occurred to me beforehand.

A rare occasion for me. I usually do the unnecessary work first before realizing the easy solution.

So I went out and plugged in a spare unit.

Three spare units actually, I have 5 hanging in the shed

(all with good plastic connectors, the one in the car is the first I've seen totally disintegrated).

Y'all guessed it, no change. All four units run when the wipers are off, intermittent or low, then speed up when switched to high.

So it's either Ben's Wiper Brain under the dash is bad or the Rotary Gods are playing tricks on me.

At this point I'm betting on the Rotary Gods.

But I still gotta do the Wiper Brain. Ben, you wouldn't have a photo or diagram of where that Wiper Brain is located would you?
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Old 11-08-18, 04:44 PM
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I'll take a picture when I get home today. Fortunately, it's probably the easiest thing under the dash to get to, so that's a bonus. I'll also grab a shot of the wiring diagram if you want - could be helpful in figuring out how the thing works.


Well I was looking for a photo that I KNOW I took of the internals of the wiper computer, but I can't find it. I'll take a picture of where it is under the dash like I said before.
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Old 11-08-18, 05:11 PM
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Originally Posted by Qingdao View Post
I'd take a look in the motor. There is an "off" spot inside the motor itself. If it has grounded out or somehow malfunctioned it could cause draw and a "rampant wiper" situation.
^^^This in reference to "park" circuit that always cycles wipers to base of windshield when turned off.

Ray,before you swap out delay timers and possibly damage one 1st try to split the wiper circuit in half. This may help eliminate part of harness,circuit,component and help steer you to which way to go.
Turn key on,wipers running? Leave key on,wiper switch off and remove connector from wiper switch,do wipers keep running or stop mid cycle?
Can think of three possibilities: Faulty delay timer,pinched/broken wire in control part of harness or commutator in wiper motor corroded/pitted or park position terminal came unsoldered or broke off.
Start with simple stuff 1st.
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Old 11-08-18, 07:48 PM
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Mike you are talking above my pay grade and intelligence, I can work with one variable at a time but not three.

But hopefully you will be able to explain what I'm about to report, cause it looks to me it is the Rotary Gods messing with me after all.

Let me explain.

So Ben is right, finding the Wiper Brain is relatively easy once you get over your phobia of working under the dash.

Once I found it I immediately unplugged it to confirm it was indeed the Wiper Brain - voila, the wipers turned off.

Here's the unit sitting on my kitchen counter top:



Now this is how I know it's the Rotary Gods and not some rational explanation.

When I plugged the Wiper Brain back in, the wipers started working again when in the off and intermittent positions, just as before.

So I unplugged the Wiper Brain again and tried the wipers with the Wiper Brain removed.

Yep, you guessed it, the wipers worked perfectly.

Off when turned off, intermittent in the intermittent position, slow on the slow, fast on the fast.

Not believing the Rotary Gods could be this devious and that there must be some reason why the Wiper Brain is in the car, I took it out for a test drive.

With the Wiper Brain still sitting on my kitchen cabinet counter top.

Car runs perfectly, wipers work perfectly, everything is perfect.

And I have a Wiper Brain for sale.

So thanks to all who helped me through this emotionally stressful problem and please remember the Moral of the Story:

Trust in the Rotary Gods, even when your faith is being tested, they will care for and protect you and your RX-7

Last edited by ray green; 11-08-18 at 08:08 PM.
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Old 11-08-18, 08:43 PM
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Well that's interesting.... Not sure how that would work. It also appears as though they changed the design of the brain somewhere from '80 on. Mine looks like this:


Don't mind the rust, the car sat in a field for 16 years before I bought it.

Interesting nonetheless. Not sure why that would have solved it, but I guess if it worked, great!
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Old 11-08-18, 09:12 PM
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Say Ben, you wouldn't mind doing an experiment and seeing if your wipers still work after unplugging that SA Wiper Brain would you?

I'm curious to know if brainless wiper function is a feature of all RX-7's or if instead my car is possessed.
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