Delay Module location

[1low4x4]

So, my wipers are controlled by the 2 speed switch on the dash right now. Although I installed a newer column out of an 85 with cruise and delay wiper switch. Can someone walk me through the steps of making the wipers work from the column stalk and also the delay?

 

[chengny]

Hey Dave,

Here is the description of operation for the intermittent wiper system:

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The two step test procedure (at the bottom):

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A marked up wiring diagram showing the two test ground leads.

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A couple of things:

1. The dwg doesn't show it correctly. The two harnesses will need to be connected to the module - as they would be for normal operation.

2. The procedure mentions that a fused jumper is required, but unless you have one handy, I wouldn't worry about the fuse. Just a jumper should be fine.

3. Because everything will be tightly snapped together, you'll have to be a little bit inventive to get the jumper in contact with the GRY 91 leads.

 

[Norwester]

Jerry, Doesn't seem too difficult, except maybe trying to make contact while the connectors are hooked up.

I assume I can just use a test light?

We have a bunch of snow on the ground but I'll get to this when I can and let you know what I find. Thank you again.

 

[Norwester]

Well, that was interesting.....the snow melted so I went out with my trusty test light.

Both connectors were attached to the module. I poked and prodded the gray wire on both sides of the module and this is what I found:

Switch off: Light came on both side of the module

Intermittent: Light came on both sides of the module

Lo and High: No light on either side of the module

This seemed odd to me so I checked it several times. I'm 99.9% sure I was getting good contact.

Bear in mind that my lo and high wipers work fine.

While the wiper motor is fairly new, could it be bad?

 

[Norwester]

Rechecked.....I wasn't sure I was in the right wires. Turning the module over, I see that the gray wire was in the 4th position on the motor side and in the 5th position on the switch side, as your troubleshooting pictures show.

 

[Norwester]

Jerry, Not sure where I'm supposed to attach the ground. I just clipped the test light to the edge of the dash and now I'm thinking I should have attached it to the connectors. Your diagrams aren't very clear on that.

 

[chengny]

Jerry, Not sure where I'm supposed to attach the ground. I just clipped the test light to the edge of the dash and now I'm thinking I should have attached it to the connectors. Your diagrams aren't very clear on that.

Hey Dave,

I wouldn't use a test light for this diagnostic - just make the connection (from the GRY 91 to ground) with a straight jumper. Make the jumper out of a length of wire that is similar in diameter to the GRY 91 lead. Cut a piece that is long enough - such that it is able to reach from the module to the common grounding bus block.

It is not necessary, but clipping your lead to the block will help ensure full continuity to ground. Clipping onto the dash is sometimes hit or miss when trying to establish a good ground path. This is primarily due to a lack of unpainted surfaces.

The common ground bus block is on the sidewall just outboard of the e-brake actuator:

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One end (the one for the bus block) should have an alligator clip. The other end should terminate in such a way that you can kind of insert it down into the gap between the GRY lead and the casing of the connector. Always remember that it has to establish and maintain a good connection.

The best way would be to cut the GRY lead. Attach your jumper to the incoming side of the cut (i.e. for test #1, the side that goes to the wiper motor) and conduct the test. Then, when you are done with the that test, splice it back together. If there is no positive result from the first test, do the same thing on the other side of the module for the second test.

But that method is kind of drastic, so try to find a work around before doing it that way.

 

[Norwester]

Ok...I think I understand although I think I was getting contact on the dash. I made up a jumper wire with an alligator clip on one end and I soldered a small gauge nail to other end. Ought to be able to make good contact in those connectors. I'll mess with it again when our new snow stops

Question though.....In the troubleshooting guide above, it says to put the ignition to "run" and then to turn the wipers to low, and then conduct the test. My wipers work fine on low so I'm not sure what this test will show....working down the troubleshooting procedures,it says to replace the switch.

Given that my delay doesn't work, should I put the switch on delay before I run the two tests?

 

[Norwester]

One other thing.....I don't remember ever seeing a common ground block near the fuse panel. My kick panel is carpeted and I know there isn't one on that. I'll have a look though around the area though

 

[chengny]

I'm sorry Dave. I thought you had an intermittent problem with LO speed and no pulse operation at all. I think I was helping someone else with that condition and carried it over to your problem.

Let's check the wiper switch - specifically that twisting the end of the stalk provides the module with a variable resistance.

Looking at the schematic above, from what I can see it appears that the resistance (which controls the sweep rate) is varied across the two BRN leads. The BRN leads are in the outermost slots of the connector. Unclip the connector (switch side) from the module and use your multimeter to test for a change in resistance from the BRN to the BRN. I have no idea what the range of resistance should be. But just as a first step, make sure it is at least changing.

Start with the knob at the slowest end of frequency. Get an ohmic value across the two BRN leads and then twist the knob to the fastest end and get another resistance reading.

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[Norwester]

Not exactly sure how to use the meter to do that but I'll figure it out....or maybe even read the instructions

 

[Norwester]

Ok....went online and learned how to measure resistance.

Started the engine and set the delay to "slow"

Applied probes and measured .2

Turned stalk to delay "fast" and measured .4

Took second reading after about 3 minutes and the readings went up to .4 and .6 respectively

The meter measured out to thousandths but the above figures were rounded down

I guess I need to know what the resistance needs to be. I have no idea where I'd find that.

Do you think this indicates that my switch harness is ok?

 

[Norwester]

Would it tell me anything if I disconnected the module on the motor side and applied the probes to the module itself?

 

[chengny]

Not exactly sure how to use the meter to do that but I'll figure it out....or maybe even read the instructions

Would it tell me anything if I disconnected the module on the motor side and applied the probes to the module itself?

Nah, that won't work - don't even bother. That's because there is no variable resistance to even measure on the load (motor) side of the module. The sole purpose of the variable resistance - that which is created by twisting the knob (and rotating the guts of the switch) - is to send a signal to the module indicating what sweep rate the operator wants. The module can "understand" that change in resistance and uses it to generate a pulsed path to ground on the GRY 91. Basically, it receives an analog signal and converts that into a digital output.

The point is, the variable resistance signal goes into the module and that is it - it ends there. It doesn't have anything to do with the other side. The two BRN 96 leads don't even pass through the module. That is why there are seven (7) leads coming into the module from the switch and only five (5) going out to the motor. As we discussed, everything after the switch/module is the same - whether the system is pulse or non-pulse.

On this:

Started the engine and set the delay to "slow"

Applied probes and measured .2

Turned stalk to delay "fast" and measured .4

Took second reading after about 3 minutes and the readings went up to .4 and .6 respectively

The meter measured out to thousandths but the above figures were rounded down

I guess I need to know what the resistance needs to be. I have no idea where I'd find that.

Do you think this indicates that my switch harness is ok?

IDK for sure, but I would say that, yes. It would appear that you have proven proper operation of the variable resistor and the wiring to the module. I don't believe we will ever be able to find the actual range of resistance - by looking on the internet or in manuals. I guess GM believes that some things are simply not meant to be known by mortal man.

The best way to get that info would be for me to get off my lazy ass, go down to my nearly gutted truck and get some ohm values from slow to fast sweep rate. I know that my switch is good (I am starting to doubt myself on whether I sent you a good module). Bear with me for a couple of days and I will come up with that info for you. My truck is only about 15 minutes away - waiting to have the frame sandblasted - and I have to see the blast guy anyway.

The operation of the GM pulse wiper system isn't widely understood. But I'll tell you one thing; when we are done with this project, you will know as much as anyone about how it works.

BTW - this is not a normal circuit, so what you did worked this time. But for future reference, you should never try to measure resistance in a live circuit. Not that you will get hurt or damage anything, but doing it that way will oftentimes result in skewed readings. When measuring resistance across a component, it should be de-energized and removed from the circuit.

 

[Norwester]

Should I redo it with the engine off?

I scoured the internet and I DID find a troubleshooting guide that talked about measuring ohms in a wiper switch. I have no idea what kind of a vehicle they were testing. Their delay had 6 different settings and they were supposed to register .2-.6 In line with my reading but again, I have no idea what vehicle they were testing.

You're right...I am learning a great deal...thanks to you