2 Speed Wiper Issue

[mrwfp]

We have been trying to resolve a two speed wiper motor issue on a friend's car.  We have a two speed wiper motor installed along with a 1971 two speed wiper switch.  Both the switch and the motor have good grounds.  The wiper motor post with the copper ground strap is grounded to the car engine block with a 6 gauge strap and also to the firewall.  The switch has a 12 gauge wire soldered to the case that grounds to both the dash chassis and to the car frame. When the wipers are turned off, 4 out of 5 times the wiper motor reverses and parks. However, it never parks in the same location.  The wipers reverse and park at various locations on the windshield.  About every 5th time, the motor reverses and continues to run in reverse. The motor was sent back to the rebuilder who said that there is nothing wrong with the motor. Works perfectly on his bench.  We have used 2 different correct switches that were also verified as good with the same results.  What is causing this?  A bad motor or 2 bad switches that the rebuilders won't admit are bad or something else?

[Jay Bee]

Do the harness and resistor check out okay?

[mrwfp]

There is continuity from end to end on each wire through the harness. Disconnecting the resistor causes the low speed not to work. So the assumption is that the resistor is good. I don't think bypassing it would make a difference.  One of the other mysteries is that the 1971 only switch has a 7th blade at the 6 o'clock position.  On other forums, people claim this 7th blade on the switch is for ground. When a ground wire is attached to this 7th blade, the main 20 amp fuse blows when the wiper switch is turned on. There is also a 6 inch long black with white stripe wire coming out of the same harness as the 4 plug and 2 plug wiper switch connectors. I cannot find any wiring diagram that calls out this black/white wire or a 7th blade on the switch.  When buzzed out, this black/white wire does not go to ground and it also does not seem to have current when the switch is on in any position. It was assumed that since this wire came out of the wiper switch harness, it must go to that 7th blade. Whether this black/white wire is connected to the 7th blade of the switch or not, there is no difference in how the switch and motor behave. The windshield squirt button on the switch works with or without this wire attached also.  By the way, the car in question is a 1971 Charger Super Bee. We have tried the B body forums for an answer but get only smart alec responses or the usual grounding issue responses. We made sure grounding was good as we reassembled the dash and chassis and installed the switch and motor. I was hoping maybe someone here might be able to shed some light on what we cannot find in that forum.

[Jay Bee]

On Ebodies that "7th blade" is not used. I think I read somewhere once that it's only for testing the switch but don't quote me.

Funny story, decades ago when I was learning I tried for days to position the connector so that all the blades would be used. Finally gave up, connected as in the picture and was pleasantly surprised that the wipers worked as they should with one empty terminal.

Your black/white wire is still a mystery to me.

PS: I just read that you wrote your "windshield squirt button on the switch works". 1970/71 two speed Ebody wiper switches don't have electric squirt capability, only the variable speed does. Are B-bodies different in that respect?

[mrwfp]

Thank you for the reply.  Apparently, the 2 speed B body switch has a squirt capability.  Or at least the one year only 1971 switch has the squirt button.  Looking at a troubleshooting diagram and how to test the motor without the switch, it shows 2 different ways to provide power/ground and jumpers to the motor plug. One way for a car with retractable headlights and one without retractable headlights.  I do not understand what the headlight configuration has to do with the wiper motor wiring. We will just have to keep digging into this to figure out why the motor runs good in low and high speed but will not park in the same position every time or reverses and keeps running in reverse. Wiper electrical issues that I have had with my 'Cuda were similar and were due to bad grounds. Those were fixed with the addition of the same ground wires that we put on the Charger's switch and motor.

[Jay Bee]

Is the "reversing cam" set-up the same as an E-body, maybe something is off or broken with that. I also found a procedure for testing a 2 speed wiper motor.

[mrwfp]

Jay Bee you are coming up with some good ideas.  The cam set up is the same and it appears to be correct.  When the motor reverses and parks, the small arm on the motor stops at various points but never in the same spot.  The motor was checked out by the rebuilder and he claims that the motor reversed and parked correctly 10 times in a row on his bench.  In the car it hasn't parked in the same place twice in a row yet, with or without the cam and long arm attached.  We had the procedure you just posted but did not try it yet as we first wanted to make sure which wire was P1 and P2. The picture we had made it difficult to determine which was which and I did not want to mis-ID a connection and ruin the motor.  This evening I found another picture that also showed the color coding of the wires. So we will try this procedure next week. I am sure it is going to be something simple, like the ground, but we have good grounds between the switch, the instrument panel, to the dash frame and to the car body and also with the wiper motor to the firewall and the engine block.

[Jay Bee]

Just in case you didn't catch this thread here's 4 pages that may or may not help,
https://forum.e-bodies.org/electrical-and-audio/11/please-help-with-2-speed-wiper-motorwiring/377/
Can't wait to hear what it ends up being.

[chargerdon]

My two cents says its the wiper motor.  My wiper motor went bad couple of years ago.   

I found the least expensive way of repairing was to buy a NEW one from Advance Auto parts that is WAI brand for two speed wipers.    Perfect fit, works perfect...cost only $52 right now with free direct shipping to your home.   They also have a "Premium" rebuilt for $82 plus core. 

Nope, the new WAI isn't an original Mopar part...but...IT WORKS and is inexpensive and it looks 95% like the original.   

But, im driving a driver quality Challenger not a Mecum show car.