[V8] Intermittant IC ground and Oil Pressure warning light fixed!

Ingo Rautenberg IRautenberg at comcast.net
Sat Sep 25 11:30:33 EDT 2004

OK.  I finally figured out what was causing my IC problem.  First let me
explain what enabled me to finally figure it out.  I have been driving
without my dash pad for the past few weeks.  When the ground for the Water
temp and fuel gauges would disappear I found that often by pushing forward
the top of the IC while driving contact would be restored...for a while.
Sometimes this didn't work and I found that fiddling with the loom at the
back of the IC attached to the yellow plug, the contact would also be
restored -- but I still had the aggravating oil pressure warning display and
chime come on intermittently.  So last evening I once again removed the IC
and took off the main back panel containing the boards for the computer
warning display and then proceeded to remove both circuit boards.  When
laying on the workbench (or in my case kitchen table) and with the warning
display at the top, I first removed the screws attaching the right side
circuit board, as that one plugs into the left side (see green plug on
left -- this turns out to be the critical area).  I used Deoxit to clean the
pin contacts there and the long strip of contacts in the middle of the right
circuit board.  Then I reassembled and reinstalled in the car.  Drats, the
low oil warning light came on almost immediately.  It was late and I decided
to bag it.

This morning I made an interesting discovery:  Two pins from the IC were
laying together in my work area from the night before!  Hmm, out goes the IC
and I disassembled once more to find that the missing pins belonged to the
left circuit board where the right circuit board plugs into the left one and
with a third pin about to fall out!  I think there are eight pins in total.
So I removed the left circuit board and resoldered all of these pins... the
solder joints were all suspect.  Reassembled and Voila!  No more warnings
and I believe this will definitely take care of the problem.  Now all my
previous experiences made sense.  Bad solder joints on these pins.  So
before I replaced the board, I press-fitted the two boards together to make
sure the pins were securely soldered in and then screwed them back into the
white plastic back of the board.  Don't forget to plug the warning chime
into the plug on the right of the board.  I would have taken pics, but I
left both digicams at the office yesterday!


'91 200q20v...Slightly modified
'84 Urquattro
'91 v8q 5-speed w/ lots of mods :-)

----- Original Message ----- 
From: "Ingo D. Rautenberg" <ingo at waratap.com>
To: "V8 List" <v8 at audifans.com>
Sent: Friday, July 30, 2004 11:22 AM
Subject: [V8] Intermittant IC ground Q

> Patient:  '91 V8 5-speed
> I was wondering if anyone found the source of the fuel guage and water
> guage going to zero. I guess for some it's not an intermittant thing.
> Previously, I'd just whack the top of the dash --not too hard, mind you
> Lately, on  bumps in the road the guages will come on/ off.  It also
> the Seatbelt warning light to come on when the circuit is completed.  So
> obviously an intermittant contact -- but where?  Any BTDT advice before i
> rip into this thing?
> -Ingo
> '91 200q20v...Slightly modified
> '84 Tornado Red Urquattro
> '91 v8 quattro 5-Speed (not exactly stock) :-)
> http://hometown.aol.com/quattringo/index.html
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