1999 GMC Sonoma Problems
RepairPal has identified the most common problems with the 1999 GMC Sonoma 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 headlight switch used on the GMC Sonoma is known to fail through normal operation. Since the headlight switch is also integrated into the interior lights, a malfunctioning switch can cause issues with interior lights as well.
- Symptoms of a failed headlight switch include:
- Headlights and taillights failing to turn on or off
- Interior lights flicker, or fail to turn on or off
- Gauge cluster lighting off or flickering with headlights on
- Parking light malfunctions
This issue is well known with General Motors Trucks and SUVs, and is solved by testing and, if needed, replacing the headlight/dimmer switch. Bad grounding wires at the tail-lights, and dirty/corroded tow package wires can also lead to some of these issues.
The heater core under the right side of the dashboard may leak engine coolant which can puddle on the passenger front floor. The loss of coolant may cause an engine overheating condition. Our technicians tell us that removal of the dash board is necessary to replace the heater on these vehicles.
The distributor may develop internal faults. This can cause a rough running engine or stalling condition and the Check Engine Light may or may not illuminate. The distributor should be overhauled or replaced to correct this concern.
A fluid leak may develop from the transmission output shaft seal. This leak may cause the transmission mount to become oil soaked and require replacement of the mount along with the leak repair.
Vehicles equipped whit a 4 speed automatic transmission may develop a harsh 1-2 shift and/or illumination of the Check Engine Light with code P1870 stored. This can be caused by wear of the bore for the TCC isolator and regulator valves in the valve body. This condition does not commonly occur until the transmission reaches normal operating temperature. If the valve body is worn, replacement will be necessary to correct this concern.
A Loose or worn gas cap may cause Check Engine Light to illuminate.
The serpentine belt tensioner can fail; it may become noisy and/or the belt may jump off. Replacement of the failed tensioner will be necessary.
On vehicles with intermittent windshield wipers, the wiper motor circuit board may fail and cause the wipers to stop working at times. Replacing the circuit board should resolve the issue. 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.