99 Blazer Headlight flickers

On occassions my 1999 Blazer headlights flickers when I hit a bump. It doesn't happen all the time. I have had it in the shop and they can't find anything wrong. One mechanic suggested the body computer might be bad. I have pulled and bumped everything, but I can't make the lights flicker. Any suggestions?

On occassions my 1999 Blazer headlights flickers when I hit a bump. It doesn't happen all the time. I have had it in the shop and they can't find anything wrong. One mechanic suggested the body computer might be bad. I have pulled and bumped everything, but I can't make the lights flicker. Any suggestions?

Have you unconnected the electrical connectors to that actual bulbs and clean and reinsert them?

That and check all your grounds.

Sounds like your mechanics should be avoided, the computer doesn't control the headlights so I have no clue why they mentioned that for.

Oh yes, well as LT said check those but also see if they flicker or could be the mounting bracket (composite plastic) is broken in one of the locations such as the top closer to the hood. Those 2 plastic flat slides that stick up behind the front support behind the headlights hold them in so pull straight up and then the whole assembly comes off - check for broken mounts - had one and same effect over bumps.

Oh yes, well as LT said check those but also see if they flicker or could be the mounting bracket (composite plastic) is broken in one of the locations such as the top closer to the hood. Those 2 plastic flat slides that stick up behind the front support behind the headlights hold them in so pull straight up and then the whole assembly comes off - check for broken mounts - had one and same effect over bumps.

Would this cause both headlights to flicker at the same time?

Doubt it unless both broken and thats a stretch. How is the alternator - is it about 14v on the gage - low output could also cause. My 99 looks like the light flicker when I have the factory fog lights on (switch on headlight switch) as they always bounce alittle on big bumps and thats normal.

Doubt it unless both broken and thats a stretch. How is the alternator - is it about 14v on the gage - low output could also cause. My 99 looks like the light flicker when I have the factory fog lights on (switch on headlight switch) as they always bounce alittle on big bumps and thats normal.

My lights actually goes out for a few seconds and then comes back on. The park lights, tail lights or any other lights do not flicker at all. I will check the alternator output.

Check the headlight relay and all wiring going to the headlights.

Does this happen on both hi beam and dim?

Does this happen on both hi beam and dim?


Yes. It happens on hi beam and dim. When it happens, no other lights are guages change. They stay constant.

The bumps are probably causing a connection to come loose

do what blazerLT said

There is a remote possibility that the ballast is shorting intermittently, or the HID lamp itself has the cathode shorting periodically. You could switch the lamp from one side to the other and see of the problem moves with the lamp or remains with the fixture.

This, of course, is all in speculation that you have HID headlamps.

Blazer's didn't come with HID.