GMC C3500HD 1991-2002 Windshield Washer Pump Replacement Guide
Everything you need to know to replace the windshield washer pump on your GMT400-era heavy-duty truck.
- Failure is typically a dead motor, clogged lines, or a leak from the pump's grommet.
- Replacement is a simple, 30-minute DIY job; the pump press-fits into the reservoir.
- Before replacing, check the fuse and test for power at the connector to rule out electrical issues.
- On GMT400 trucks, a faulty wiper control module on the firewall can prevent a good pump from working.
Is Your Windshield Washer Pump Failing?
A failed washer pump on your C3500HD can be more than an annoyance; it's a safety issue, especially in bad weather. Because this part is simple, the signs of failure are usually straightforward.
Common Symptoms of a Bad Washer Pump:
- No Fluid Spray: You activate the switch, the wipers move, but no fluid comes out. This could be an empty reservoir, but if it's full, the pump is a likely suspect.
- Pump is Silent: You don't hear the familiar humming or whirring sound of the small electric motor when you try to use the washers. This points to a dead pump or an electrical problem.
- Pump Hums, But No Spray: If you can hear the pump running but no fluid sprays, the pump may have failed internally, or you could have clogged lines or nozzles.
- Weak or Uneven Spray: A pump that is wearing out may not be able to create enough pressure, resulting in a weak stream that doesn't effectively clean the windshield. This can also be caused by clogged nozzles.
- Visible Leaks: You may notice washer fluid pooling under the front of your truck. The pump body can crack, or the rubber grommet that seals it to the reservoir can degrade and leak.
Check This First: The Wiper Control Module
On these GMT400 trucks, the washer pump is controlled by the wiper motor's control board, often called a pulse module, located on the firewall. It's a known issue for this board to fail due to corroded solder joints. If you replace your pump and it still doesn't work, and you've confirmed the fuse is good, the wiper control module is the next place to look.
Choosing the Right Aftermarket Pump
For a 1991-2002 GMC C3500HD, finding an original OEM washer pump can be difficult, and often unnecessary. The windshield washer pump is a simple, non-critical engine component where a quality aftermarket part provides a reliable and cost-effective solution. Brands like Trico specialize in wiper and washer systems and offer direct-fit replacement parts.
The Trico 11-513 is a commonly available aftermarket pump for this truck. Reviews indicate it is a dependable, direct-style replacement that is easy to install and restores strong spray performance. These pumps are typically made from durable plastic and are designed to fit into the original location without modification.
Installation Tip
Aftermarket pumps are designed to fit many vehicles. Sometimes the outlet port for the hose points in a different direction than your original pump. On many designs, you can simply turn the body of the pump to get the correct angle before you install it. Also, test for 12-volt power at the pump's electrical connector with a multimeter before installing a new pump to rule out a blown fuse or wiring issue.
Cost of Replacing a Windshield Washer Pump
Replacing the washer pump is one of the more affordable repairs for your truck. The part itself is inexpensive, and if you do it yourself, the cost is minimal. Even having a shop do the work is relatively cheap, as it's a quick job.
| Part or Service | Estimated Cost |
|---|---|
| New OEM (AC Delco) | $23 - $45 |
| New Aftermarket (Trico) | $29.34 |
| Shop Labor | $50 - $100 |
| DIY Total (Aftermarket) | $29.34 |
| Shop Total (Aftermarket) | $80 - $130 |
Frequently Asked Questions (FAQ)
Can I replace the C3500HD washer pump myself?
Yes, this is a very easy DIY job that typically takes 15-30 minutes with basic tools. The pump is usually located at the bottom of the washer fluid reservoir in the engine bay. It is held in by a press-fit into a rubber grommet. The process involves unplugging the electrical connector, pulling off the fluid hose, prying the old pump out, installing a new grommet, and pressing the new pump in.
I replaced the pump and it still doesn't work. What now?
First, check the fuse labeled for the wipers or washer pump (often "WW PUMP") in the fuse box. If the fuse is good, the problem could be clogged washer lines or nozzles; try clearing them with compressed air. A more complex issue on these trucks can be a failed wiper control module on the firewall, which actually controls the pump's power.
Do I need to replace the rubber grommet?
Yes. Almost all new washer pumps come with a new rubber grommet, and you should always use it. The old grommet can become hard and brittle, causing leaks even with a new pump. Remove the old grommet from the reservoir before installing the new one.
Could the problem just be clogged nozzles?
Yes. If you can hear the pump running but the spray is weak or non-existent, the nozzles may be clogged with wax or debris. You can try cleaning them with a small pin or needle. If the pump had been broken for a long time, it's common for the nozzles to get clogged from disuse.
Technical Specifications
OEM Part Numbers: 8-6710
Fits 1991-2002 GMC C3500HD. Includes pump and new reservoir grommet. Aftermarket part numbers include Trico 11-513.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- GMC C3500HD: