98 TJ instrument cluster problem SOLVED - JeepForum.com
 2Likes
Reply
 
LinkBack Thread Tools
post #1 of 24 Old 08-18-2008, 07:13 PM Thread Starter
Bill C
Registered User
1998 TJ Wrangler 
 
Join Date: Dec 2007
Location: So Cal
Posts: 139
98 TJ instrument cluster problem SOLVED

Back in February I bought a '98 TJ and it's quite clean The only problem it had that REALLY bugged me was an intermittent dash gauges cluster failure. They would work...then go off...then work for a couple of days...then off for a while...with NO RHYME OR REASON.

Jeep had a TSB (08-15-99) on May 21, 1999 about this problem. The repair suggested by this TSB had been done by a dealer and supposedly fixed the problem for a year or two, but then the problem came back.

I tried the "twist the pins" repair as suggested elsewhere on this forum, but that didn't work. So now I had to look at the whole circuit.

The cluster gauges get their info over a two wire "data buss". The TSB repair was to replace one of the Molex connectors that plugs into the instrument cluster. That was the first place I looked. The repair from the dealer looked bullet-proof. There was evidence that the splices were soldered, and the splices were also moisture proof heat shrinked. Looked great. One problem, however, was to access the wires, I needed to disconnect the cluster. I messed with all those wires, and the problem always came back. I looked at all the splices, connections, and wire runs. No luck.

Now was time to start at the beginning. I went back behind the cluster. This time I removed the connectors from the dash mounts so I could plug them into the cluster with it out of the dash. I could now make the problem come and go, but still not consistently.

I re-read the wiring diagram to verify the "data buss" wire colors and noticed that they should be a "twisted pair". When the dealer did the repair, they didn't twist the data wires. I decided to cut out the splices, twist the wires, and re-splice them.....PROBLEM SOLVED....
I don't know if the lack of twist was the problem (inductance...impedance) or if one of the splices was bad, but the problem was in that couple of inches of wiring.

Hope this helps others with the same problem.


As an electrician I always advise:
"Remember, it's only a shock if you don't expect it" :-)
Bill C is offline  
Sponsored Links
Advertisement
 
post #2 of 24 Old 02-24-2011, 12:15 AM
credto
Registered User
1999 TJ Wrangler 
 
Join Date: Dec 2009
Location: Montesano
Posts: 115
airbag light

was your airbag light on when the gauges flat lined, and is this fix still working....thanks

O|||||O
credto is offline  
post #3 of 24 Old 02-24-2011, 12:26 AM
TheBoogieman
Disturbed Jeepaholic
 
TheBoogieman's Avatar
2003 TJ Wrangler 
 
Join Date: Aug 2006
Location: CharlottesHELL
Posts: 38,062
Quote:
Originally Posted by credto View Post
was your airbag light on when the gauges flat lined, and is this fix still working....thanks
He's probably sold the Jeep by now.
TheBoogieman is offline  
 
post #4 of 24 Old 02-24-2011, 06:37 PM Thread Starter
Bill C
Registered User
1998 TJ Wrangler 
 
Join Date: Dec 2007
Location: So Cal
Posts: 139
Quote:
Originally Posted by credto View Post
was your airbag light on when the gauges flat lined, and is this fix still working....thanks
I can't truly remember if the airbag light was on or off when the gauges quit, it probably was on but I can't be sure, but to answer your question, yes the gauges are still working great.

I don't remember my gauges flat lining... I think that they just became unresponsive till I turned the Jeep off, then they went down.

I have another situation with the airbag light, sometimes I still have that problem where when I just have started the Jeep, the AB light is on, and NONE if the other electrical is working....no gauges....no CB....no radio. This I have found is the ignition switch. The key sometimes sticks between the start position and the run position.......... All I do is help it back to the run position and everything goes back to working. If your gauges are dropping, I'd start there.

Hope this helps

As an electrician I always advise:
"Remember, it's only a shock if you don't expect it" :-)
Bill C is offline  
post #5 of 24 Old 02-24-2011, 06:40 PM
Wheelin98TJ
JEEP FREAK
 
Wheelin98TJ's Avatar
1998 TJ Wrangler 
 
Join Date: Apr 2004
Posts: 26,420
Quote:
Originally Posted by TheBoogieman View Post
He's probably sold the Jeep by now.
Who would do such a thing?

I've had my TJ since '99 and I don't think I'll ever sell it.
Wheelin98TJ is online now  
post #6 of 24 Old 02-24-2011, 06:42 PM Thread Starter
Bill C
Registered User
1998 TJ Wrangler 
 
Join Date: Dec 2007
Location: So Cal
Posts: 139
Quote:
Originally Posted by TheBoogieman View Post
He's probably sold the Jeep by now.
ARE YOU KIDDING........... THAT'S MY BABY

As an electrician I always advise:
"Remember, it's only a shock if you don't expect it" :-)
Bill C is offline  
post #7 of 24 Old 07-22-2011, 08:57 AM
rag165
Registered User
 
Join Date: Apr 2011
Location: st marys
Posts: 1
Instrument cluster problem repair

Quote:
Originally Posted by Bill C View Post
I can't truly remember if the airbag light was on or off when the gauges quit, it probably was on but I can't be sure, but to answer your question, yes the gauges are still working great.

I don't remember my gauges flat lining... I think that they just became unresponsive till I turned the Jeep off, then they went down.

I have another situation with the airbag light, sometimes I still have that problem where when I just have started the Jeep, the AB light is on, and NONE if the other electrical is working....no gauges....no CB....no radio. This I have found is the ignition switch. The key sometimes sticks between the start position and the run position.......... All I do is help it back to the run position and everything goes back to working. If your gauges are dropping, I'd start there.

Hope this helps
I did this "retwisting the wires" fix on 2 jeeps now and they are both still working. The airbag light was on with my 98 Wrangler when the gauges went out. Sometimes only my speedo and tach went out other times everything went out. I cut out the factory splice and resoldered the data bus wires with the twists in. I removed the tape far enough back so i could see the original twists in the wires. When retwisting the wires make sure to twist in the same direction as the original twists and try to get the same amount of twists per inch. Take the twists as close to the connector as possible. The speed of a communications wire is actually determined by the amount of twists per inch in the wire. Untwisting the wire will change the impedence of the wire and also cause signal reflections.
rag165 is offline  
post #8 of 24 Old 07-22-2011, 01:34 PM Thread Starter
Bill C
Registered User
1998 TJ Wrangler 
 
Join Date: Dec 2007
Location: So Cal
Posts: 139
Quote:
Originally Posted by rag165 View Post
I did this "retwisting the wires" fix on 2 jeeps now and they are both still working. The airbag light was on with my 98 Wrangler when the gauges went out. Sometimes only my speedo and tach went out other times everything went out. I cut out the factory splice and resoldered the data bus wires with the twists in. I removed the tape far enough back so i could see the original twists in the wires. When retwisting the wires make sure to twist in the same direction as the original twists and try to get the same amount of twists per inch. Take the twists as close to the connector as possible. The speed of a communications wire is actually determined by the amount of twists per inch in the wire. Untwisting the wire will change the impedence of the wire and also cause signal reflections.
So I'm not crazy after all.......... Good to know.

As an electrician I always advise:
"Remember, it's only a shock if you don't expect it" :-)
Bill C is offline  
post #9 of 24 Old 07-22-2011, 01:58 PM
NotURMailman
Web Wheeler
 
NotURMailman's Avatar
2005 TJ Wrangler 
 
Join Date: Nov 2006
Location: 'Round Here
Posts: 8,221
Any time a data circuit is supposed to be a twisted pair it needs to stay that way. Engineers may do some stupid things some times, but when they do that it is for a good reason!


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
equipped... And loving it!

I drive on the right side, what's wrong with you?


Quote:
Originally Posted by Deacon View Post
It's difficult to take you seriously. It's like you're an easily perturbed autistic teenager who's drunk typing the whole time.
NotURMailman is offline  
post #10 of 24 Old 09-24-2011, 06:39 AM
Dnahas
Registered User
 
Join Date: Sep 2011
Location: Huntingtown
Posts: 2
I can't seem to shake this problem... New harness, slightly bent pins... What do you mean by "twisted pair"? Do I just twist the two bus wires togethe? Which direction? (dealer did the replacement harness and everything is directly connected). Right now my brake light comes on, but no check engine or gauges are working.
I really don't want to buy a new cluster... Help
Dnahas is offline  
post #11 of 24 Old 09-24-2011, 09:44 AM
troy.j
Registered User
1999 TJ Wrangler 
 
Join Date: Mar 2007
Location: wa
Posts: 376
Quote:
Originally Posted by rag165 View Post
The speed of a communications wire is actually determined by the amount of twists per inch in the wire. Untwisting the wire will change the impedence of the wire and also cause signal reflections.
The twisted pair is to protect data from outside noise being inducted into the wires. The data line and return line are twisted together so that any Electro Magnetic Interference (EMI) is canceled between the two. It has little to do with impedance and even less to do with data rate.

A lot of the time EMI is the cause of noise in a CB because the power wires are not shielded and pick up noise from the sparkplug wires or other things in the vehicle. Any electrical motor and your alternator are also sources of EMI.

The twisted pair cheaper means of shielding wires then using coax and takes up less space however, it is less effective. Look in a telephone box at a business some time or CAT-5 cables for computers.

How do I know? 20 years of aircraft wiring repair and over 4 years of school provided by Uncle Sam.

99 tj, 00 wj, 95 yj

...ask those who have bled of the cost of freedom and honor those who gave that others may have what we take for granted...
troy.j is offline  
post #12 of 24 Old 09-26-2011, 06:07 AM
Dnahas
Registered User
 
Join Date: Sep 2011
Location: Huntingtown
Posts: 2
You've got to be kidding me... Per the advice here, I looked up the wire diagram in the service manual... Sure enough- twisted pair; violet/brown with white/black.
When the dealer install the TSB harness, they neglected to do this.
I cut the splice, twisted the two wires and re-sodered....
Perfect.. All is working.
Thanks for the help
Daxon likes this.
Dnahas is offline  
post #13 of 24 Old 02-20-2013, 07:31 PM
rayw
Registered User
2010 JK Wrangler 
 
Join Date: Jan 2013
Location: Herod
Posts: 36
Have to bump this thread to say thanks. I had run the gamut of gauge repairs (reseating, grease, twisting pins) in stages and nothing was helping with my speedo/tach dropping out. After reading this thread I checked and the bus wires were not twisted so I fixed them up and everything has been working for over a month now. Special thanks to Dnahas for identifying the wires to check/twist.
rayw is offline  
post #14 of 24 Old 02-20-2013, 09:03 PM Thread Starter
Bill C
Registered User
1998 TJ Wrangler 
 
Join Date: Dec 2007
Location: So Cal
Posts: 139
I'm glad to see that this was a real fix and not just a coincidence I stumbled upon.

As an electrician I always advise:
"Remember, it's only a shock if you don't expect it" :-)
Bill C is offline  
post #15 of 24 Old 05-20-2013, 11:28 PM
Muddy82
Registered User
 
Join Date: May 2013
Location: Pittsburgh
Posts: 1
Great post! I will be trying this as my tj too flatlines and the AB light comes on.
Muddy82 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Instrument cluster problem casualjeeper TJ Wrangler Technical Forum 1 05-23-2008 06:07 PM
Instrument Cluster Problem! Need Help rfenn TJ Wrangler Technical Forum 6 05-19-2008 07:06 PM
Instrument (Cluster) Panel Problem! rfenn TJ Wrangler Technical Forum 0 05-18-2008 08:42 AM
Instrument Cluster Electrical Problem. SCouch TJ Wrangler Technical Forum 7 08-07-2005 09:14 AM
For those with the Instrument Cluster Problem... JTJ98 TJ Wrangler Technical Forum 7 09-30-2003 01:49 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome