Dim H4

ErVikingo · 10-07-2008, 06:03 AM

Guys,

One of my H4's is dim (left side). Bulbs are fine. Time to check grounds or ?

javadog · 10-07-2008, 06:07 AM

Ground or valtage issue. Check and clean the connections first then break out a meter and measure the voltage and resistance to ground at the bulb.

JR

ErVikingo · 10-07-2008, 06:47 AM

Thanks JR. Any values in particular I'm looking for?

john walker's workshop · 10-07-2008, 07:09 AM

see if the wire colors are arranged the same on both plugs.

scottb · 10-07-2008, 09:45 AM

Assuming wiring is correct, my guess would be ground. I had a similar problem on a 72 240z, and replacing the ground wire fixed it.

javadog · 10-07-2008, 06:49 PM

Quote:

Originally Posted by ErVikingo

Thanks JR. Any values in particular I'm looking for?

As close to zero ohms as possible for the ground and as close to battery voltage (as measured across the two terminals) as possible for the positive wire. When in doubt, you can measure the good side and compare.

JR

rgrimm · rgrimm's Garage

Unless you're absolutely certain the wiring is correct, what John Walker's said. A friend was about to throw away the lights on his 930 until as a last effort he looked at how the three wires were connected. A PO had wired the plugs wrong. The lights appeared to work normally...but were dangerously dim.