Interrmittent windshield wiper: Fixed

I have a 2000 Chevy Venture.

For a long time (several years), my wipers operated intermittently. At first, the wipers sometimes got stuck and would not return to the “park” position when turned off. They would return to “park” (most of the time) if the engine was turned off and later restarted. Sometimes the so-called “pulse” selections would work for a while and then quit. Usually, selecting fast would clear the windshield as a last resort because it worked most of the time.

When it rained, it was a pain in the butt trying to find a wiper selection that worked but one could usually be found. Finally, one rainy day, none would work. I couldn’t procrastinate getting the problem fixed any longer so I had to either fix it myself or have it done by a shop or the dealer.

For some time while my wipers were misbehaving, it was bothering that I had no idea as to how or what controlled my wipers once I moved the wiper switch to a particular selection.

So, as when I have had other car problems, I first went to the Forum and read all posts I could find about wiper problems. Then I went to my Haynes Repair Manual to see what it had to say.

It had some good information like signal names on the harness connector and removal/installation instructions of the windshield wiper motor assembly. What was missing was the info that there is a circuit board which controls the motor (attached to the motor assembly) which may or may not be replaceable as a separate part from a vendor but could be salvaged from a junk yard.

Also, in one or more of the forum posts, the possibility of cold solder joints on the circuit board was mentioned. Having been an Electronics Engineer in another life, and repairing many electronic devices with cold solder joints, over the years, it seemed logical to take a look at that before obtaining new or used parts.

The rest of this has to do with what was done to fix the circuit board (which was successful) but if you don’t have the proper equipment or skills for circuit board repair, you can quit here.

I won’t go into the detail that can be found in Haynes (check your local library for a Haynes or equivalent) but I’ll try to give some pointers in dealing with the circuit board.
1. Assuming that you know how to remove cowl covers to expose the wiper motor (ignore instructions about removing the washer reservoir because it’s unnecessary), check that the signals at the harness connector are correct (see Haynes). If not, the problem might be upstream in the steering column switches or wiring.

2. If the harness signals are correct (Haynes doesn’t give voltages for the Low/Pulse pin (E) but they vary by several volts for each position on the steering column switch), then the motor assembly must be removed.

3. Before removing the motor assembly, pry-off the crank cover (plastic cover held by small tabs) and using a marker pen, trace the position of the mechanical parts of the crank arm (assuming the wiper blades are in the “park” position. This will help immensely in getting everything to work upon reassembly. Haynes mentions a V-notch in their alignment process that I failed to notice and which made alignment impossible unless done correctly. The spring loaded do-dad with the V-notch needs to be engaged with a tab on the motor mounting bracket when the motor shaft is connected to the crank arm. It was very hard for me to see the V-notch so make sure you see the connection between it and the tab it connects with.

4. Once the motor assembly is removed, use a TORX T20 tool to remove three screws holding the circuit board to the motor assembly. Unfortunately, the solder connections are on the bottom of the board so the board must be removed from its case.

5. The circuit board is held in place by two (2) tabs on the sides and a cam connected to a shaft with a press-on spring ring. To make removal of the board easy, pry the locking spring ring off first (use a very sharp and strong prying pin on a couple of the prongs to remove the ring). I’m not aware of a device that does this! But if there is, I don’t have it!
Once the locking ring and cam are removed, pry the board out of its side tabs with a screw driver inserted between the board and side tab. On reassembly, press on the board at the side tabs and it will lock in place.

6. In viewing the circuit board from the soldered side, there are some very large printed circuit traces on one side while the other side has very narrow traces. The side with very narrow traces contains transistors, diodes, and other components. This side has a conformal coating that is relatively thick and does not lend itself to reheating solder joints. In addition, it’s highly likely that applying heat some of the sensitive components might destroy them. As a result, heat should only be applied to joints that can withstand re-soldering but in addition are the most likely candidates of cold solder joints.

7. Re-solder those connections associated with the wide traces and in particular with pin out connections to the motor connectors, harness connector, and relay connections (the large black cubes on the component side of the board). Chances are that with LUCK, this may fix the problem.

8. To see how lucky one is: reassemble the board, reattach the board to the motor assembly and connect the harness connector to the motor assembly (it’s not necessary to fasten any of the mechanical stuff). Turn the ignition key to ON (without starting) and set the wiper to its various positions. The wiper motor should run continuously at high and run/stop at other positions. If this happens, you have successfully re-soldered a circuit board with the most significant of cold solder connections. Reassemble and re-lubricate the windshield wiper unit.

9. If not, find replacement parts and follow the procedure at step 8.

Yeah, very typical GM repair, fixed one for some poor sucker at a gas station 1/2 way between kansas city and columbia, MO and it was pouring rain and he was stuck, used my butane soldering iron to do that one.......