Our purpose is to support owners in their use and maintenance of the Porsche 928 and to foster camaraderie among owners throughout the world.
Welcome, Guest
Username: Password: Remember me

TOPIC: Looking for a fuse box diagram

Looking for a fuse box diagram 15 Jan 2010 17:29 #70


  • Posts:3176 Thank you received: 3
  • 928mac's Avatar
  • 928mac
  • Moderator
  • OFFLINE
  • Karma: 3
Now that I am starting to diagnose my fuel gauge not working.
I discovered that there is no diagram for the fuse box
1989 928 s4 Japan import

Electronic PDF or JPG would be great
Thanks
The administrator has disabled public write access.

Looking for a fuse box diagram 21 Jan 2010 00:32 #75


  • Posts:3176 Thank you received: 3
  • 928mac's Avatar
  • 928mac
  • Moderator
  • OFFLINE
  • Karma: 3
I found the fuse diagrams in the manuals at this link

sorry, I think it was half way through #6

http://www.cannell.co.uk/Manuals.htm
The administrator has disabled public write access.

Looking for a fuse box diagram 23 Jan 2010 13:13 #76


  • Posts:995 Thank you received: 9
  • Kiln_Red's Avatar
  • Kiln_Red
  • Moderator
  • OFFLINE
  • Karma: 2
Need some more details about your fuel gauge in order to really benefit you in troubleshooting the issue.

Has the car ever sat for longer periods without ever running? Also, the easiest way to determine if the gauge itself isn't functioning is to disconnect the harness from the opposite tab of the instrument cluster that supplies power to the temperature and fuel gauges. Though, I am unfamiliar with your car's cluster, I assume it is basically the same as any 928 I've ever worked on.

On the bottom of the instrument cluster there should be two harnesses attached to two independent tabs. The one on the right is the one you would want to disconnect with the key turned to the on position. This will create a temporary voltage spike to the temperature and fuel gauges. If both gauges are in good working order, then your fuel gauge will read full and your temperature gauge will indicate head warping, gasket failing, fry an egg over the hood value. Note: Be careful in removing either harness from its position beneath the cluster as it's rather easy to break the small tabs they're attached too.

If that test shows positive results, then it's MOST LIKELY that your sending unit has failed. No sweat. This doesn't mean that you must automatically buy a new one. Mine failed in my '84 and I just removed it, took it apart, and sanded the rod that the little float must travel against. Years of letting the car sit with fuel inside shot the pump and the sending unit. The rod within the sending unit obviously came in contact with bad fuel therefore allowing it to rust and further ceasing any transitioning of the float. This caused my gauge to read the same value all of the time.
The administrator has disabled public write access.

Looking for a fuse box diagram 24 Jan 2010 00:03 #79


  • Posts:3176 Thank you received: 3
  • 928mac's Avatar
  • 928mac
  • Moderator
  • OFFLINE
  • Karma: 3
KilnRed;79 wrote:
Need some more details about your fuel gauge in order to really benefit you in troubleshooting the issue.

Has the car ever sat for longer periods without ever running? Also, the easiest way to determine if the gauge itself isn't functioning is to disconnect the harness from the opposite tab of the instrument cluster that supplies power to the temperature and fuel gauges. Though, I am unfamiliar with your car's cluster, I assume it is basically the same as any 928 I've ever worked on.

On the bottom of the instrument cluster there should be two harnesses attached to two independent tabs. The one on the right is the one you would want to disconnect with the key turned to the on position. This will create a temporary voltage spike to the temperature and fuel gauges. If both gauges are in good working order, then your fuel gauge will read full and your temperature gauge will indicate head warping, gasket failing, fry an egg over the hood value. Note: Be careful in removing either harness from its position beneath the cluster as it's rather easy to break the small tabs they're attached too.

If that test shows positive results, then it's MOST LIKELY that your sending unit has failed. No sweat. This doesn't mean that you must automatically buy a new one. Mine failed in my '84 and I just removed it, took it apart, and sanded the rod that the little float must travel against. Years of letting the car sit with fuel inside shot the pump and the sending unit. The rod within the sending unit obviously came in contact with bad fuel therefore allowing it to rust and further ceasing any transitioning of the float. This caused my gauge to read the same value all of the time.

Thanks Kilnred;

I disconnected the fuel sender lead with the key on and then jumped it across both wires to test for a faulty sender, or rather to see if the fuel gauge moved. It didn't. that was before I got the fuse box diagram. I haven't gone any further.
I guess what you are saying is that the power for the temp sender and fuel gauge are the same? and the temp gauge works.
Looks like I will be doing your test and will have to remove the cluster. Crap!
The administrator has disabled public write access.

Looking for a fuse box diagram 25 Jan 2010 13:33 #83


  • Posts:995 Thank you received: 9
  • Kiln_Red's Avatar
  • Kiln_Red
  • Moderator
  • OFFLINE
  • Karma: 2
You don't have to take your cluster apart. Just adjust the wheel to its tallest point so you can access it that way. This should allow you plenty of room. If your gauge jumps now, then you'll know there is a fault in the wiring. Are there any other instruments not functioning correctly?
The administrator has disabled public write access.

Looking for a fuse box diagram 25 Jan 2010 19:31 #85


  • Posts:3176 Thank you received: 3
  • 928mac's Avatar
  • 928mac
  • Moderator
  • OFFLINE
  • Karma: 3
KilnRed;86 wrote:
You don't have to take your cluster apart. Just adjust the wheel to its tallest point so you can access it that way. This should allow you plenty of room. If your gauge jumps now, then you'll know there is a fault in the wiring. Are there any other instruments not functioning correctly?

The only other electrical issue is that the cluster information center stays on after the key is removed. It only goes out after the doors are locked with the key. That is the other thread that I started
The administrator has disabled public write access.

Looking for a fuse box diagram 27 Jan 2010 10:14 #89

http://928intl.com/repair.htm
as link to relays/fuse panel
The administrator has disabled public write access.
Moderators: Rich928, mm928, billvvOC
Time to create page: 0.152 seconds