I replaced the plugs and plug wires on my 99 jimmy 4.3 4x4, 133k miles. I used AC 41-993 plugs and Belden premium wires. The job went perfectly. I didn't have to force any wiring harnesses out of the way or re-route any wiring. I took the truck for a test drive. I saw that the battery light on the dash was coming on for 2 to 4 seconds intermittently and randomly. The battery light had never come on prior to replacing the plugs and wires. I can't imagine how changing the plugs and wires could cause this, but it must have, how could this be some kind of coincidence? There are no other symptoms. The dash voltmeter doesn't even flinch when the battery light comes on, it just holds at 14 volts, as if everything is fine. I've been driving the truck like this for 3 days now. It doesnt matter if I'm on a bumpy, gravel road or smooth, paved highway, the battery light still comes on intermittently. The battery is only 6 months old. The alternator is 9 or 10 years old with about 90 or 100k miles on it. About the only things I've done so far to try to fix this is to disconnect the battery for 20 minutes, clean the battery terminals, make sure the battery terminals are tight, Look for any arcing at the plug wires in the dark (no arcing, the truck runs good) and inspect all wiring and connections. Not sure what to do next. I bought this good ol' truck back in 2000 with 12k miles. It's been great with very few problems over the years. I can't afford to start replacing alternators, coils, distributors and stuff until the problem disappears. Before I take it to the shop, I thought I'd ask you guy's if you have any ideas about this.

 

Could be a coincidence, or maybe not, it needs to be checked out to make sure. Using a DVOM, connect the probes to the battery terminals and check voltage while the engine is at ~1500 rpm, and all accessories turned off. Voltage should ideally be 14.2 volts, and hold steady. Have an assistant watch the battery light on the dash, if it comes on, notice if the voltage reading changes.


Another possibility is a poor solder joint on the instrument cluster circuit board where the vehicle harness plugs in. If/when the light comes on, using an open hand, give a little rap, straight downward, directly above the center of the cluster. See if the light blinks or goes out.

 

I took the truck to Oreillys and the local repair shop. Both places tested the alternator and battery and they checked ok. The repair shop said that since it was intermittent, it could still be the alternator. So I decided to throw in a new alternator, and a new coil. Took a chance on Oreillys Ultima Select alternator( it's new, not rebuilt), but I wanted to make sure I got a nice coil, so I bought a Borg Warner coil..... Drove the truck on a 100 mile trip to nowhere, just to be sure it's ok. Looking good now!!