Date: Sat, 21 Feb 2009 20:30:10 -0800
Reply-To: mark drillock <mdrillock@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: mark drillock <mdrillock@COX.NET>
Subject: Re: Help troubleshoot my instrument cluster
In-Reply-To: <213954.26602.qm@web83710.mail.sp1.yahoo.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
VW combined many instrument cluster items to a single ground wire on the
14 pin connector. Then they combined that single ground wire with a
bunch of other dash ground wires all into one final wire which then runs
to the main ground star. When everything was working fine, say for 15-20
years, this combined ground system was ok. Now we are past that point.
You likely have a bad ground for the instrument cluster. When a ground
gets flaky, some of the anxious electrons look for another path to get
home. Sometimes they try to flow backwards into a wire for something
else if that looks like their best escape route. That can make other
things on those escape routes act screwy.
The first simple step is to put the instrument cluster on a dedicated
ground wire. Just cut the brown wire to pin 3 of the 14 pin connector,
leaving a few inches. Splice some more wire to the cut end that is now
hanging from the 14 pin connector. Put a ring end on it. Screw that ring
down to bare metal in the dash area. Hopefully in a spot where it will
be noticed if someday in the future someone is checking out another
problem with the ground. You don't need to do anything with the other
cut end of the brown wire going down into the dash. Tape it off if it
makes you feel better but do not attach it to anything.
(pin 3 of the 14 pin connector is only the ground wire for 85-91
clusters, and the rare 84 tach cluster)
If that step does not solve the problems the biggest thing left is the
spring pins in the 14 pin connector itself. They can loose their tension
or get bent from being plugged in and out. If you look closely into the
open edge at the spring pins you can see if the brown wire's pin has a
problem. With care and good light you can put a touch more curve in the
pin so it sticks up into the opening slightly more to make stronger
contact. This will make the curved edge a tighter fit when it is plugged
back onto the cluster.
Mark
James Ballen wrote:
> Hey folks,
>
> Hopefully some collective wisdom from the group can help me figure out what's going on with my instrument cluster wiring.
>
> I have an '86 wolfsburg weekender that came with an analog clock cluster.
> PO installed a cluster from an '85 w/a tach.
> Everything works except a few things:
>
> -the coolant temp sensor does not work with the headlight switch turned on. I had the boys at Buslab fix this about a year ago...Marco told me it was a shorted wire somewhere...and it worked fine until the other day when it started happening again. Pin #6 on my dash connector (coolant temp sensor) has a wire butt-spliced onto it that goes down to the back, bottom left of the fuse/relay box. I can't tell exactly what it's plugged into, but I think it's a relay. Not sure why it's spliced, but it was working fine until a couple days ago. Temp accuracy was verified with an infared temp gun.
>
> -once the coolant system is nearly up to operating temp, the tach sits up around 4k. Once the engine is revved up to ~1800 the tach then reads accurately. As soon as it goes back to idle, the needle shoots back up to 4k. While it's warming up, the needle reads accurately around 900 at idle, but introducing other electrical loads affects the reading. For example, if I turn on my headlights, the tach needle jumps up a bit, or if I turn on the turn signal, the tach will bounce in time with the blinking.
>
> -the coolant LED sometimes flashes a longish amount of time upon startup before going out. I know the coolant level is good.
>
> Things I've done:
>
> I acquired another cluster from another '85 van.
> Symptoms are exactly the same. This should rule out the cluster being the problem...
> With my meter, I measured 0 ohms resistance on the pin #3 ground to chasis ground, so the ground should be good...
> I unhooked pin #12, the dynamic oil buzzer system, since the '85 cluster doesn't have this function, but there is no change in anything.
>
> I'm sort of at a loss. That spliced coolant sensor wire may have something to do with the coolant sensor problem, right?
>
> But that still does not explain the tachometer problem.
> I've read that there is an oil pressure sensor (I think) that starts engaging after 2k RPM, is this right? Seems like that could be related to the tach issue since they both relate to 1800-2000 RPM...but I don't know anything about it.
>
> Any suggestions are very welcome. Please PM me as I am on digest mode and sometimes don't receive posts until a day or two later.
> Hopefully I've been specific enough for you to have some ideas...
>
> Thanks!
>
> /james
>
| 
