Windshield Wiper Help

[cah2873]

Hello, we have been working on a 1984 Chevrolet K20 for several months and we are now looking at the windshield wipers. They work fine and have a low and high. The wiper switch in the steeering column is for a variable speed set up and that is what we would like in the end. However right now the wiper switch will work on mist- then low clicks into place as in pic 1- then high clicks into place as in pic 2. The 3rd pic is the motors underneath the hood. Do I have the wrong wiper switch in the column? How can make this setup variable speed? Thanks in advance.
CAH2873

 

[chengny]

Wipers with the delay option have an additional component between the switch and motor - the pulse module. If the delay feature doesn't work, but all other modes are okay, there is most likely a problem with the pulse module.

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I am not positive but I think - judging from its appearance (which is identical to the 1985 -1991 version):

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that it is located behind the lower dash/under the steering column just like in the later model years.

Remove the steel and plastic access covers under the steering column and it should be visible - it is clipped to a bracket attached to the underside of the column.

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First, check and confirm that it is actually installed. On non-delay systems, the module is not installed and the two connectors on either side are just snapped together.

If it isn't even in the circuit - that would certainly be the issue. On the other hand, if it is installed and the connectors are securely attached...you might have a dilemma on your hands if you want to replace it.

The part number for the module used in 1984 was originally 14074359 - and it was called a controller. It was superseded by part number 15598460. The model year 1984 was the only year that exact P/N was used. Consequently, there weren't many 14074359/15598460's made or available today. And the one's that are available are wicked expensive.

A quick search turned up a couple of hits. The sites below list the part for $158 and $189 respectively:


http://www.ebay.com/itm/NOS-OEM-GM-MODULE-ASM-WSW-PULSE-CONT-
15598460-/322202308021?hash=item4b04c10db5

http://www.wholesalegmpartsonline.c...-Wiper-Electrical-Parts/2753568/15598460.html

Not a part you want to buy unless you're sure it's the problem.

There is good news however. When I did the search for the part, I noticed it was discussed on a couple of forums. I read them quickly and it seems that although the part number is unique to 1984, the module is wired the same and it's connections are physically identical to the part used for the 1985-91 group. Modules bearing that part number - 15598496 - are plentiful and way less expensive. For example, Rockauto sells the original OEM part for $60.

http://www.rockauto.com/en/moreinfo.php?pk=75708&cc=1161111&jsn=297

But - to me - even that is too much money to pay for a part that will be used as a diagnostic tool. The junkyards are full of these modules. You could probably pick up a couple (in case one is NFG) for like $5.

 

[cah2873]

Thanks for the information. That is great. One question- if the truck is not wired for the pulse module, do I need a complete wiring harness for it or can I put the module inline from the wiper switch to the wipers?

 

[chengny]

One question- if the truck is not wired for the pulse module, do I need a complete wiring harness for it or can I put the module inline from the wiper switch to the wipers?


Before I try to help you on that issue, I have to ask you something; Did you even look under the dash yet - to determine whether or not there is a pulse module in the circuit?

From post #2:

First, check and confirm that it is actually installed. On non-delay systems, the module is not installed and the two connectors on either side are just snapped together.

If you had done that, you would already know whether or not the truck is currently equipped with the delayed wiper option.

Pulling those two cover plates - to verify that a pulse module is installed - requires a phillips head screwdriver and about 5 minutes of labor.

Anyway, since you don't know whether or not there is a delay system currently installed, the wiring diagrams for both versions of wiper systems are seen below.

The answer to both of your questions (about the interchangeability of harnesses and converting to delayed wipers with only the installation of a pulse module) is - no, there are some significant differences in the wiring and connectors. The text within the dwgs explains why. Matter of fact, after looking closely at the dwgs, it appears that I was mistaken when I suggested the following:

If the module were removed, the inlet and outlet connectors can just be snapped together - and you will still retain wiper function, just without the delay feature.

From 1985 on, that is true. But, from the looks of it, it seems it isn't possible with the 1984 harness connectors - they have different part numbers and the wiring does not pin out the same.

Delay system wiring (which I believe you will eventually discover you have):

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Base (i.e. non-delay) system wiring:

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Wiring connections at the wiper motor and pump:

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The GRAY & WHT leads are common - they are split off at the firewall connection block. White is the power feed. It is run straight from the fuse block, that's why it doesn't appear in either of the control wiring diagrams.

And finally, on this:

Do I have the wrong wiper switch in the column?

Since you are able to rotate the end of the MFS stalk, that indicates that you have the correct switch installed to enable the delay function.

There is not a special wiper motor specifically for delay systems. Both the base version and the delay option call for the same motor.

In the end, I think you will find that your pulse relay module is shot.

 

[cah2873]

It does not have a module under the steering wheel. But after further investigation, it does not have a intermittent wiper switch in the steering column. It has the correct blinker/wiper handle for intermittent but that is the reason for the "hard clicks" and limited movement back and forth on the handle. It looks like I need a module along with a new wiper switch for the inside of the column. I hope this will fix it.