Symptoms
Hard cold starts, long cranking, white smoke until warm, or a wait light that misbehaves. On an M1009, a bad resistor pack or a mixed 12/24-volt conversion can cook new plugs.
The fix, step by step
- Test each glow plug's resistance and check that power reaches each one during the glow cycle.
- Replace failed plugs (or all eight) and the controller or relay if it isn't cycling.
- On M1009s, confirm whether the truck still has the 24-volt starting system and the firewall resistor pack before you buy plugs.
- The plugs are 12-volt even on CUCVs, and the resistor pack drops 24 volts to 12.
Tools & part numbers
- Multimeter
- deep sockets and extensions
- anti-seize
Where to buy the parts
Diesel glow plugs, 1987 Blazer 6.2LRockAuto ↗Amazon ↗
Diesel glow plug controller, 1987 Blazer 6.2LRockAuto ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Chevrolet K5 Blazer (1973–1991) parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.