1995 Pontiac Transport Wiper Motor Fails Except on High: Diagnosis & Fix

If your 1995 Pontiac Transport's wipers only work on the highest speed (usually "HI" or speed 5), the issue is typically in the wiper motor control circuit—not the motor itself. Here's the diagnostic hierarchy:

Most Likely Causes (In Order)

1. Wiper Motor Pulse Board / Governor Module (Internal to Motor): This small circuit board inside the motor housing controls the intermittent and low-speed functions via pulse-width modulation. The "HI" speed bypasses it (direct power). Very common failure on GM minivans of this era. Fix: Replace the pulse board (~$30–60) or entire motor (~$80–150).
2. Multifunction Switch (Turn Signal/Wiper Stalk): The resistor network for speed selection can fail open on lower speeds. HI speed uses a separate contact. Test with multimeter (resistance values per service manual).
3. Wiper Motor Relay (in Fuse/Relay Center): Supplies power to motor. If contacts pitted, may pass high current (HI) but not lower currents. Swap with identical relay (horn, AC clutch) to test.
4. Wiring / Grounds: Corroded connector at motor, broken wire in harness (flex point at hatch/door), poor ground at motor mount. Voltage drop test each speed.
5. Body Control Module (BCM): On some 1995 models, BCM controls wiper logic. Rare but possible. Scan for codes.

Diagnostic Steps

1. Check fuse (usually 20A or 25A in underhood block).
2. With key ON, test voltage at motor connector on each speed setting. HI = battery voltage; lower speeds = pulsed/reduced voltage. If pulses missing → pulse board or switch.
3. Tap motor housing gently while on LOW/INT. If it starts/stops → pulse board solder joints cracking (classic).

Repair Tips

• Pulse board replacement: Remove motor (3 bolts), open casing, swap board. Solder skills needed or buy reman motor.
• Lube linkage pivots while apart—reduces motor load.
• Don't default to full motor replacement; pulse board is 80%+ probability.

Safety: Non-functional wipers in rain = hazard. Fix promptly.