Curbside Tech: A Deep Dive Into GM Wiper Systems (Part 2)

In my last posting, I discussed the General Motors depressed park windshield wiper system used on my El Camino. If you missed the article, here is a brief description of the system from an early Cadillac brochure. Since the El Kylemino did NOT come with intermittent wipers, I needed to better understand how depressed park wipers worked before I could convert over to the intermittent wiper system.

The differences between the two systems are easy to spot when you place the motors side by side


However, I discovered all my research on this older system (used on El Caminos from 1968 to 1983) was in vain, because in 1984 GM replaced the old system with a completely new system, as this picture shows.

The motor and cover assembly with the areas GM changed over the years


As it turns out, the new system has some really cool features, but also had a few tripping points, and a number of variations. This image shows the wiper motor and the motor/transmission cover, with the change points highlighted in blue. In this post, I’ll cover the system design and what it took to install it in the El Kylemino, then in Part 3 I’ll cover these differences in (excruciating) detail.

The motor and wiring stays the same between the base and intermittent wipers- Very handy indeed


First off, the cool features: When GM designed this system, the base wipers and intermittent wipers both used the same motor and wire harness. These two parts are difficult to replace, so by using common parts converting to intermittent wipers is much easier. Also, this wiper design is common to many different GM platforms, so the salvage yards have plenty of spare parts.

The base and intermittent wiper motor covers- On the outside they look the same


To make things work, the motor has an open transmission housing. The difference between the base and intermittent systems is in the motor cover. On the outside, the covers look the same, and include a pocket for the windshield wiper motor.

Inside, the covers are quite different


However, on the base cover (shown on the left) contains a bus bar to power the washer motor, while the intermittent cover (on the right) includes a circuit board with a plastic cam and a relay to power the wiper motor. The circuit board also includes two contact pads, highlighted with a red circle. These pads are an important feature I’ll discuss later. To switch from standard wipers to intermittent wipers, you need to swap over to the circuit board cover, commonly referred to as a “pulse board.”

Typical wiper switch- There’s no visible difference between the base and intermittent switches


You also need to replace the wiper switch. Starting around 1980, GM began burying the switch in the steering column, which makes the change out a bit challenging, but both switches use the same harness and wire connector.

Wire color is the only visible difference between two systems (new style on the bottom)


However, you do need to be careful, because the early wiper system switches also bolt in, and will not work with the motor on the newer system. To avoid this mistake, check the switch connector- The new system uses different wire colors.

Bolt in these parts, and voila- Intermittent wipers!


To add intermittent wipers to the El Kylemino, I only had to replace the existing motor cover with a pulse cover, then replace the wiper switch in the steering column with an intermittent switch and add a stalk with the correct markings (I also added a cruise control switch). As I said, the existing wiper motor and wiring harness work fine.

The base cover does not use these terminals- Be sure you grab a set when you scavenge a pulse cover at the junkyard!


Initially, my modification did NOT work. After careful research, I determined I missed two important pieces under the pulse cover. In order to complete the intermittent wiper circuit, there are two small contacts between the motor and the pulse cover. With the contacts in place, everything worked just fine. Of course, GM no longer services these contacts, so you either need to find them at the junkyard, or luck into them on E-Bay.

The two wire to three wire motor pigtail- Next week I’ll tell you why you might need one…


That covers the nuts and bolts of the El Kylemino wiper conversion, but I’ve identified ALL sorts of interesting information on these GM wipers, which I’ll cover next week.