1991 GMC 1500 Pickup Problems
RepairPal has identified the most common problems with the 1991 GMC 1500 Pickup as reported by actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.Refine by vehicle
The windshield wipers may not work intermittently due to a faulty wiper motor control board. Our technicians tell us that lightly taping on the wiper motor when the fault occurs should temporarily get the wipers working again. Some vehicles were recalled for this problem and some were not. You will need to check with your local dealer to find out if a specific vehicle was included.
The inside and outside door handles are prone to breaking.
The front or rear differential may develop an abnormal noise due to worn bearings or another internal fault. Our technicians tell us that a complete overhaul of the affected differential is commonly necessary to correct this condition.
The quick-connect fittings for the heater hoses tend to leak engine coolant. This problem commonly occurs because the metal housing has become brittle, which can break and cause leaks.
One or more heater & AC (HVAC) air delivery and/or temperature mode door actuator may fail. This can result in incorrect air delivery or temperature. If this occurs, fault code(s) stored in the HVAC control module should be available to assist with diagnoses.
An engine vacuum leak may develop from the throttle body gasket causing a higher than normal idle speed. Failed gaskets should be replaced.
A coolant leak may develop from the water pump. This can result in an engine overheating condition. A leaking water pump will require replacement.
The intake manifold gasket may develop and external engine oil or coolant leak. In some cases, an internal coolant leak may occur causing coolant to mix with the engine oil. Running the engine with a coolant/oil mix may result in engine damage. Replacing the intake manifold gasket should correct this issue.
Power brake systems using "hydro-boost" may leak power steering fluid from the hydro-boost unit located behind the brake master cylinder. Replacement of the hydro-boost unit is the common repair to correct this concern.