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Re: [T3] lights


On 31 Jan 2006 at 10:50, type3weezer@comcast.net wrote:

> With the VOM on ohms set at 200 (not 2K) I inserted the red probe into the
> rear light socket (touching the brass) the black lead to a ground. I would
> assume if the line was good I would get a reading of dead 0. But instead it
> reads 46.3 on both rear tail lights.

That measurement won't really tell you much. That's measuring the resistance 
back thru an unknown number of other devices to ground. If everything was 
working right I'd expect you to get a much lower value than 46 Ohms, however.

There are only 2 measurements here which might be useful: One is from the body 
(ground) of the bulb base to a known good ground (like the engine case), and 
the other is from the brass contact spring to the right point on the fuse box. 
Both measurements should be done with the key and lights off and should turn up 
close to zero Ohms once you find the right points.  

Sometimes it is necessary to pull the lamp body off the car and make sure the 
wires are correctly attached to the back of it. You can also then tell what 
wire colors you're looking for at the fuse box.  

> Now I crawled under the dash saturday to look at the fuse box. All fuses
> look good and the two wires comming from #1 and #2 fuse are grey and black
> and gray and blue and both look in good shape although I haven't tested them
> with the VOM. What I was throwing out to you guys was since this is one set
> going out from the fuse box, it has to split some where to go to each fender.
> could this be the source of a short? 

A short would blow fuses; you're looking for an "open," an incomplete path. On 
early cars the rear main wiring harness runs under the LR fender, so it's 
possible that the problem is there, but the MOST likely spots are at either 
end, or in the middle, near the voltage regulator, where the harness branches 
out and is exposed. 

I'd start with the contacts at the lamp base. They can become corroded and stop 
making good contact with the bulb. Use your DVM set to 20 volts and see if you 
sense any voltage on the brass spring contact when the lights are on. You 
should put the black lead on a known good ground and use the red lead to probe 
the brass spring. Don't let the red probe short out to the lamp base while 
you're doing this, or you may blow a fuse.

> Just another question... Does the plastic cover on the these early fuse boxes
> only clip on in one direction? When I clip mine on the numbers are upside
> down  and in reverse order (#10 is on the number one fuse. Or should I just
> be thankful I have a cover that fits my fuse box. 

I don't know about the early covers. I would expect them to fit on correctly. # 
1 should be on the left. The late covers will only fit on one way, as they are 
not symmetrical. I believe the snaps are such that they work best when you put 
in a particular edge first. Try doing it both ways; one way might just solve 
your dilemma.  

Someone else here will have more experience with the early covers.

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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