Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 7 Series / 8 Series > 7 Series - E23 / E32 (1977 - 1994)

7 Series - E23 / E32 (1977 - 1994)

Reply
 
Thread Tools Display Modes
  #1  
Old 01-16-2012, 09:12 PM
rlorentz rlorentz is offline
Registered User
Location: Walnut Creek
 
Join Date: Dec 2011
Posts: 5
Mein Auto: 1993 740iA
Question 93 740i - Instrument cluster voltage varies

On my E32 '93 740i the instrument cluster voltage seems to fluctuate. The gas gauge has worked very
rarely for months. The message display got very bright then went dead. Then the speedo and tach started making wild swings. And the temp gauge went dead. Seems like a voltage regulation problem. Is there a separate voltage regulator for the instrument cluster, or cluster and some other stuff, if so, where might it be located and is it likely causing this problem? Or is there just the main voltage regulator on/by the generator and that should be replaced. Thanks, Ron

Last edited by rlorentz; 01-16-2012 at 09:15 PM.
Reply With Quote
Ads by Google
  #2  
Old 01-31-2012, 07:22 PM
rlorentz rlorentz is offline
Registered User
Location: Walnut Creek
 
Join Date: Dec 2011
Posts: 5
Mein Auto: 1993 740iA
Update on voltage variations in E32 instrument cluster:
Bought the E32 manual by Bentley, it was great.
Didn't show any external voltage regulation, just main regulator on/by alternator.
Would have bought the Bentley book years ago if I knew it existed.

Swapped in a replacement cluster from a 1994 E32 and it worked fine.
Also tried a cluster from a 1988 E32 ( 735i ) which was not supposed to be compatible.
The 1988 cluster worked just fine, except the odometer and trip odometer did not.
They are wired differently up to 1991, again, all seemed to work, except OD and trip OD.

The replacement cluster has worked fine for 2 days and 10 miles.
So likely the voltage regulation is done on the circuit board inside the instrument cluster.
Problem likely solved. The circuit board went bad and likely too-high voltage fried the gauges
and the display one after the other. Cheers, Ron

Last edited by rlorentz; 01-31-2012 at 07:23 PM.
Reply With Quote
  #3  
Old 06-16-2014, 05:10 PM
fidolido fidolido is offline
Registered User
Location: Los Angeles, CA
 
Join Date: Jan 2011
Posts: 23
Mein Auto: 93 525i E34
On the back of the instrument cluster is a colored plug that you need to match up. That is the mileage EEPROM computer and can't be mixed or matched. The status LED can be rebuilt but if there is 'no' display, it could be a light bulb. Taking the instrument cluster out can be a bit tricky as you have to drop the steering wheel. If you get garbled lights on the status section, there are rebuilt ones on Ebay fairly cheap.
Reply With Quote
Reply

Bookmarks


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 7 Series / 8 Series > 7 Series - E23 / E32 (1977 - 1994)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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 On



Forum Jump


All times are GMT -7. The time now is 02:10 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms