[200q20v] Re: Bouncin' speedo

C1J1Miller at aol.com C1J1Miller at aol.com
Fri Sep 29 09:20:36 EDT 2000

In a message dated 9/29/00 1:44:32 AM Eastern Daylight Time, 
Doyt at nwonline.net writes:

> I have a 91 200 20v tq with 156k and it all-of-a-sudden the speedo has 
>  intermittently started bouncing when I'm driving. It will bounce 5mph+ ( 
>  50-55) Is this something electrical or mechanical? How can I fix it ......?
> Thanks


"Fixing the electronic spedometer

Date: Mon, 18 Oct 1999 08:09:18 -0400 
From: Robert Myers <rmyers-at-inetone.net> 
Subject: Bouncing speedo fix 

Several years ago I encountered the proverbial bouncing speedometer 
problem.  Since several posts have indicated that this is a recurring 
problem I am attaching the repair procedure I finally came up with to truly 
solve the problem with the '89 200tq instrument cluster.  It permanently 
solved the problem with that instrument cluster.  I suppose that the 
present problem may well benefit from the same treatment. 

Anyway, here it is: 

- ---------------------------------------------------------------------- 

   Speedo Repair 
     '89 200TQ 

  Fluctuating or pulsating needle. 

   (Also, on the GIGO principle, inoperative cruise control.) 

Note:  This information is provided for totally electronic speedometers, 
not those driven by cable. 

Cause of the problem:  A poor connection between the speedo head itself and 
the PC board of the Instrument Cluster (IC). 

Repair procedure: 

Remove the IC from the car.  (Additional info on IC R/R is available if 
this is not sufficient for you.) 

Open the hinged back of the IC and remove it.  Several Hex head screws are 
involved here. 

Remove the PC board.  There are several more screws and a few small bits 
and pieces involved.  No big deal but keep track of where everything came 
from so you can put it back later.  Note that there are four pins extending 
from  the speedo head through the PC board which provide electrical 
connection between the head and board.  (These are very similar to the 
jumper connections on many PC boards.)  It is these connections which are 
the problem. 

Remove the speedo head itself from the IC.  Follow the four pins back to 
their connections with the small PC board of the speedo head itself. 
Desolder these four pins and then replace them with separately color coded 
wires which are part of a high quality four (or more?) pin connector. 
Several types are available.  I used connectors from an RJ-11 phone 
extension cable simply because I had one immediately available.  Other 
connectors will work nicely - perhaps better.  The RJ-11s are rather bulky. 
 Extend the cable out so that it may be plugged into its mating half behind 
the IC after it is reassembled. 

Solder the other half of the connector (matching the color coding of what 
you did inside the speedo head) to the PC traces where they connect to the 
original connectors of the PC board.  Lead the cable to the outside of the 
IC again. 

Note that some slight amount of cutting of the plastic IC case may be 
needed to permit easy extension of the connectors to the outside of the IC. 
 Select your route carefully and this will be a minimum amount of trimming 
and will be a trivial job. 

Reassemble the IC and plug the two halves of the connector together.  Tape 
the dangling connector to the back of the IC to provide strain relief. 

Use of suitable and much smaller connectors will eliminate the necessity of 
doing the final connection outside the IC.  I simply used what I had on 
hand.  It might pay to find a better alternative.  The requirement is for 
four conductors, preferably color coded, and a high quality connection. 

Reinstall the IC back into the car. "
hth, chris miller, windham nh, c1j1miller at aol.com

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