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2004 gmc envoy_slt_xuv
5 Posts
Discussion Starter #1
Finally found correct third b light for SUV checked fuses but still no joy...what am I missing?

2004 chevy trailblazer_lt
63 Posts
Remove the liftgate grommet / wire and then to follow >> Access the HMSL plug connection by lowering the rear portion of the headliner releasing the headliner retaining pins.

Disconnect the plug to test.

Using a DVOM....

Check for voltage/ continuity at the source end of the plug . Make sure the DVOM probes contact the terminals. Use a paper clip if needed if terminals are too small.

MAKE SURE ! >> Apply the brake with a prop or something heavy to press it till stop switch engages.
Or a if you have help to hold the brake pedal down.

When using a DVOM this will check power and ground within the wired circuit.
Does it show voltage? >>> Then the bulb is most likely defective.

Now if it doesnt show voltage >> Check to see if its either a power or ground path thats broken attach a probe to a clean grounding point.

Attach the other probe to check voltage at the hot terminal and see if you get voltage.

If not >> That determines the Hot wire is broken path.
Find the break/corrosion...

If DVOM shows voltage via a ground point other than the wired OEM ground then you have a break with the factory wiring.

Check wire and grounding point for corrosion or break.

No DVOM ? >>> If Using a test light (same procedure) make sure you attach the ground clamp to a clean grounding point. Then Check as described above then to check Oem ground wire attach test light gator clip using that Oem circuit to check it at the terminal.

To confirm bulbs are defective then apply 12 volts to the pigtail terminal which (power to power wire - ground to ground wire respectively) would reveal it .....

Good luck. :)
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