- The problem
- Fatigue cracks may develop in the brake vacuum booster housing. This may cause a vacuum leak and reduce the effectiveness of the brakes. After prolonged use, the cracks may develop to the extent that the booster may separate from the vehicle.
- The fix
- Vehicles will be inspected for fatigue cracks in the brake vacuum booster. Those without cracks will have a support brace installed. Those with evidence of cracking will have a new brake vacuum booster and support brace installed. This service will be provided at no charge.
Vehicle safety record
1979 GMC C20 Problems, complaints & recalls
No owner complaints about the 1979 GMC C20 have been filed with NHTSA. It is covered by 2 recalls, the latest in January 1981 for the vacuum.
NHTSA data checked
DMore problems than a typical C20 year, for its age
- Complaints
- 0
- Recalls
- 2
- Crashes
- 0
- Fires
- 0
- Injuries
- 0
- Deaths
- 0
1979 GMC C20 recalls 2
Recall repairs are free. Your dealer fixes them whether or not you bought the car there - check your VIN at nhtsa.gov/recalls to see if yours is done. What to do
- The problem
- On the involved vehicles the brake stoplight and cruise control switch which is operated by the brake pedal may have been assembled with an incorrect lubricant on the actuating plunger. This can cause the rear brake stoplights to become inoperative and the cruise control, if activated, to stay electrically engaged.
- The fix
- Dealer will inspect and, if necessary, replace the brake stoplight and cruise control switch at no cost to owner.
What owners say
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No complaints about the 1979 GMC C20 yet
No owner has filed a complaint about this vehicle with NHTSA. If yours has a problem, share it here and report it to NHTSA.
GMC C20: every year compared
All C20 years1979 GMC C20 vs rivals
| Vehicle | Complaints | Recalls | Grade | |
|---|---|---|---|---|
| 1979 GMC C20 | 0 | 2 | D | |
| 1979 GMC GMC | 2 | 3 | D | Compare |
| 1979 GMC C2500 | 1 | 1 | D | Compare |
| 1979 GMC Bus | 1 | 0 | F | Compare |
| 1979 GMC C Series(light) | 1 | 0 | C | Compare |
More sales usually means more complaints, so compare similar vehicles of the same year. The grade compares each vehicle with its own model's other years.
Questions about the 1979 GMC C20
Does the 1979 GMC C20 have any recalls?
Yes - NHTSA lists 2 recalls for the 1979 GMC C20: vacuum (January 1981); switch (June 1979). Recall repairs are free at any authorized dealer. Enter your VIN at nhtsa.gov/recalls to see whether yours has been fixed.
How many complaints has the 1979 GMC C20 had?
None have been filed with NHTSA so far.
Is the 1979 GMC C20 a reliable vehicle?
Its Safety Index is 26 out of 100 (grade D: more problems than a typical GMC C20 year, for its age). The index weighs complaints, crashes, fires, injuries, deaths and recalls against how long the vehicle has been on the road, compared with the same model's other years. It is not a measure of every repair - read the complaints and owner experiences, and have any used vehicle inspected before you buy.
What should I do if my 1979 GMC C20 has a problem?
If it is a safety problem, stop driving it if it is unsafe and contact your dealer. Report it to NHTSA at nhtsa.gov/report-a-safety-problem - enough reports start investigations and recalls - and share your experience here so other owners know what to look for.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) complaints and recalls, checked . Complaints are owners' own reports and are not verified. How we use the data