speedo not working

For the M Powered Z3 derivatives

Moderator: Gazza

Post Reply
transcup
Joined: Sat 15 Jun, 2019 17:46
Posts: 10

  blank

speedo not working

Post by transcup » Sat 21 Mar, 2020 17:54

Hello Help needed Z3M
Speedo worked perfectly before winter lay up.
Went out in it last week and it was intermittent / kept stopping altogether then finally flicked up and down a few times now dead. No movement at all
Done cluster test and everything including speedo work.All other gauges are operating as normal
Changed speedo sensor on Diff today , still dead.
Pulled out relevant fuses OK.4/7/23/27/31/46
Removed cluster and reseated connectors.
All seem ok but nothing .
What else should I check and how ,
Could it still be a cluster fault even though speedo does not work when driving?
Any ideas

User avatar
Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 10089

  Z3 roadster 1.9
Location: Cheshire

Re: speedo not working

Post by Robert T » Sat 21 Mar, 2020 18:45

Put the odometer into self-test mode and select the speed display. Readout is in km/h. If it reads zero it is not getting any input. Full details of self-test mode in the knowledgebase.

Cheers R.

Sent from my SM-G960F using Tapatalk

Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Image

transcup
Joined: Sat 15 Jun, 2019 17:46
Posts: 10

  blank

Re: speedo not working

Post by transcup » Sat 21 Mar, 2020 20:15

Can you explain a bit more please
If I manage to get it into this mode do you have to drive it to see if Speedo increases or not?
Not sure if I understand how to put it into this mode, will look at knowledge base again , don’t want to cause another issue

User avatar
Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 10089

  Z3 roadster 1.9
Location: Cheshire

Re: speedo not working

Post by Robert T » Sat 21 Mar, 2020 23:01

Self-test mode is really useful and lets you do some basic testing without the need for diagnostic kit.

All the gauges are driven by digital to analogue converters. The inputs from the various systems on the car are all digital. The idea is to check the speed signal before it goes through the DAC.

Yes, you will need to drive the car to get a speed reading.

I have had an intermittent fault on mine where periodically (about once every six months) all the gauges will shut down, but the car drives normally, the miles get counted etc. In this case the cluster seems to detect an electrical fault and shuts down the gauges to protect them. They come back to life if I turn the ignition off long enough for the immobiliser to cut in.

Hope that helps explain what the test is intended for.

Cheers R.

Sent from my SM-G960F using Tapatalk

Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Image

transcup
Joined: Sat 15 Jun, 2019 17:46
Posts: 10

  blank

Re: speedo not working

Post by transcup » Sun 22 Mar, 2020 15:19

Hello
Removed cluster re connected everything
Managed to do self test as suggested
Yes it shows digital revs
When set to kph nothing on 8
What do I need to do next?
Is it the cluster or loose connection some where
Any more checks to do

User avatar
Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 10089

  Z3 roadster 1.9
Location: Cheshire

Re: speedo not working

Post by Robert T » Sun 22 Mar, 2020 15:31

Difficult to say whether it is the cluster or not, but it does seem to be somewhere on the input side i.e. from the pick up on the diff to before the DAC.

By the sound of it, it is a loose connection or possibly a broken wire. I would check the cable and connector on the diff end where it is exposed first. If that is all good, then the next place to look is for chafe points where the wiring loom comes up through the dash into the back of the custer. Last suspect is the cluster itself and it could be a bad joint on it that needs resoldering, but rule the other bits out first.

At least it is a persistent problem, so you should know when you have found/fixed it. I can't even reliable reproduce mine to attempt fixing it!

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Image

transcup
Joined: Sat 15 Jun, 2019 17:46
Posts: 10

  blank

Re: speedo not working

Post by transcup » Wed 25 Mar, 2020 16:34

Hello Robert
Thanks a lot for your help
Spent 6-8 hrs looking at this
Cluster out numerous times , checked wiring , checked cables where I could but nothing
I then looked again at connector on speedo sensor
Looked perfect no signs of damage, finally buzzed out cables to dash cable 4 ok but nothing on cable 3 one to fuel sensor. Removed carpet ect to get here, nothing.
Finally knowing it was cable 3 tested cable just up from connector to pin to fuel sensor, nothing after hours finally found problem.
Took Speedo sensor connector apart nothing obvious wrong, put pin in cable just above connector and tested nothing so soldered new cable into connector and it now seems to work
Will give it a full test tomorrow
Never had this type of failure before, very hard to find
The positive is o now know how to remove cluster ,and other things
Hope you track yours down
Keep safe with Coronavirus
Steve

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests