Which parts fail
Components named in complaints (battery, alternator, wiring, ignition, instrument cluster, infotainment).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2003 GMC Sierra owners, lightly cleaned up (personal details are redacted by NHTSA).
On May 31st, the rear end differential assembly exploded sending the pinon thru the housing and the rear axle caught on fire. The truck was in the shop (perry cheverolet, inc., columbia, mo)until 6-9-03. When I arrived in bozeman, mt on 7-2-03 I was having problems with the wiring. There was a fire when I plugged the rv electrical plug into the truck's trailer plug. There was also a blown rear tail light bulb. In bozman, they replaced the complete wiring harness, the tow receptacle and 2 fuse kits. It was the opinion of the shop in bozeman (j.c.billion, GMC) that the wiring damage was part of the original fire and differential assembly damage. Although GMC paid for my out of pocket expenses and for the waranty work, I am left to wonder what will happen next and just how safe am I going to be in this truck? …
Summer 2007 we received a notice from GMC for our 2003 GMC Sierra that stated "your vehicle could develop a condition where one or more of the instrument panel gauge needles May stick, flutter, or become inoperative. This May cause inaccurate readings, including the speedometer and the fuel gauge." they offer to correct this problem if it occurs in vehicles within 7 years or 70,000 miles, whichever is less. Our GMC Sierra developed this condition recently at 5 years and 90,000. The speedometer began to display inaccurate speeds and eventually started erratically pulsing and sometimes displaying no speed. This is very unsafe to have this happen when you are driving. There are numerous entries online indicating that this has happened to many of the vehicles in the 5 year range, many just after the mileage cut off. …
Instrument cluster inoperative. 2003 GMC Sierra pick up. Received a letter from GM and due to the mileage they will not repair the cluster even though the vehicle is within the date range. The mileage listed is not reasonable since they only allow 10K per year. They were called when I received the letter at 104K and now at 111K they can only apologize for the problem but not fix it under warranty. I feel it is a safety issue but they do not. So I am having it fixed for almost 600 dollars with no help from GM. This should be a recall since they knew of the problem and it has occurred enough to warrant sending out letters notifying the owners of a potential problem.
Vehicle goes into reduced engine power mode at interstate speeds without warning and increases risk of being rear ended, does not have enough power to safely get the vehicle off the road when in the left lane with other cars behind. More instances of this same scenario over the past few months than I can count. Throttle body has been cleaned. There are too many internet forum posts detailing many different parts having been replaced by dealerships and other mechanics and the problem still existing to just start replacing parts because the costs too quickly is unsustainable.
Tl contact owns a 2003 GMC Sierra. While driving approximately 65 MPH under any conditions, the vehicle's odometer fails. The failure occurs when the vehicle stops and starts. The contact would have to shut the vehicle off and restart it in order to make the speedometer work properly. The failure occurs intermittently. The dealer stated that the instrument panel needed to be replaced. The current and failure mileages were 27,051. The speedometer would not function after driving 45 minutes when on cruise control. Updated 06/13/07.
Tl* the contact owns a 2003 GMC Sierra. The contact stated that the vehicle was parked and the engine was turned off when he heard a noise and noticed that the air conditioning blower had independently activated. The failure recurred and the battery was disconnected in order to deactivate the blower motor. The vehicle was taken to the authorized dealer where the blower motor resister was replaced. The manufacturer was made aware of the defect and they informed there was no recall. The approximate failure mileage was 111,000.
The transmission clunks when shifting from 2nd - 3 rd and at times the engine will rev and finally it will take off, this has caused an issue when going through an intersection. The dealership attempted four repairs and it is not fixed. The issue started when the vehicle had 6K miles on it and it is getting worse. The speedometer is sporadic in that it will show speed reduction/increase in segments - as if it were sticking. The erroneous speed indication causes an issue when going too slow or too fast in traffic.
Tl* the contact owns a 2003 GMC Sierra hd. The contact stated that the wiring system caused the battery and the alternator to malfunction. In addition, the dash cluster malfunctioned and the reduced engine power warning light remained illuminated. The contact had to restart the vehicle for the dash cluster to function properly. The contact took the vehicle to the dealer where he was advised that there was an unknown electrical issue with the vehicle. The vehicle was not repaired the failure mileage was 170,000.
Day time running light burned out. When I replaced it the bottom of the bulb was burned and the plastic wiring socket was partially melted and brittle around the bulb base. I changed the bulb and the light still works. However, I also had trouble with one of my two horns not working, but after replacing the burned out bulb, both horns worked. Wiring seems to be in series with horn(s) and burned out bulb disables horn.
2003 GMC Sierra pick-up I was driving today about 45 to 50 miles an hour and was running great and about an hour later, my speedometer went up to 120 miles an hour and would not go back down. When I got home and put my vehicle in park, the speedometer would only go down to 70 miles an hour. I have almost 68,000 miles on it. What is wrong and what can I do to get this fixed immediately before I get a ticket?
Electrical complaints in other Sierra years
Frequently asked questions
How common are electrical problems on the 2003 GMC Sierra?
NHTSA has 31 complaints about the electrical system of the 2003 GMC Sierra, 15% of the model year's 206 complaints. The component named most often is instrument cluster/panel (19 mentions).
Is there a recall for 2003 GMC Sierra electrical problems?
No. NHTSA lists no electrical system recall for the 2003 GMC Sierra, though it has 6 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2003 GMC Sierra electrical problems start?
Half of the complaints with a recorded mileage happened before about 65,000 miles, and 15% before 25,000 miles.
Is it dangerous?
Owners linked 0 crashes, 1 fire and 0 injuries to electrical system problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.