Instrument cluster issues

[95-540iLE]

I have read through all the previous posts and had a play but still dont seem to have all the answers I need.

Until today, my H23 had the original si batteries. There is some evidence that they have leaked onto the circuit board. Some pics of its innards are set out below:




Problems I have been experiencing are as follows:
- speedo intermittently working - usually not
- econometer the same
- temperature sometimes working - lately not moving off dead cold
- night time illumination of cluster intermittent - usually not

Changing the batteries seems to have had no impact. All problems remain.

I also replaced the lights for the illumination and tightened the temperature gauge screw. Again, to no effect.

I will move next to the wire and sensor for the speedo on the diff, but even if this fixes the speedo problem, it wont fix the temp gauge or the illumination.

Any suggestions?

Thanks guys.

Regards

[Brianmoooore]

Print side of that board looks well past saving to me!
It may just be the way it looks in the photo, but it appears that cast areas of print are corroded.
The one probable fault you haven't mentioned is what the ten SI board lights do or don't do!
Speedo and board illumination are unlikely to be anything to do with the SI board, and the econometer can't function without a speed input.
Speedo problems are probably centered around the back of the car, as you surmise, and, for the dial illumination, assuming all the other dash illumination is OK, I would check the condition of the soldering of the white and blue socket pins, on the main board.

[95-540iLE]

Thanks Brian. Yes, the circuit board is corroded as a result of battery acid spill. It seems like it happened a long time ago as everything was well dry.

I am thinking that between the corrosion and old and possibly cracked solder, the board is proably beyond redemption.

Second hand clusters command a high price here and there is no guarantee of getting a good one. As such, the wider I can cast the net the better. If I recall correctly, I read somewhere that you say a board out of the later E30's will work. Is that correct? I presume if that statement covers the boards with the blue connector for the coding plugs, I would also need an M20 plug to ensure the tacho works?

My cluster is a Motometer by the way.

Finally, I have also read that the connector for the speed sensor on the diff is the same as that connected to the side lights and the fog lights. Is this correct? If so, this should be an easier find than a working cluster!

Thanks again.

[95-540iLE]

The story contiues ... In view of my fried looking circuit board, I decided to bite the bullet and purchase a tested working cluster from a breaker. Cost A$195 (over 100pounds).

I have today swapped the clocks (to retain my 'Hartge' labels) over into the 'new' cluster. To my surprise, the cluster has a new circuit board factory fitted with lithium batteries. It looks like someone has forked out to buy the oem replacement board for this cluster.

Net effect is that my temp gauge is again working. Speedo still not, but suspect that is still the wiring/sensor on the diff. Illumination is at least partly working - hard to tell because too bright and sunny here. Will have a look when it gets dark around 9.30pm.

Now the speedo. I also purchased from the breakers a fog light plug and a section of wire. Cost me A$25! I hadn't had a chance to check the speedo sensor plug and couldn't remember what it looked like, but assumed it would be the correct one given what I had read here. I should have checked.

Here are the pics of the speedo sensor plug (black) and the fog light plug (yellow).

Interestingly, the speedo sensor wiring looks to be in good shape. Is there a chance the problem could be the sensor itself?




Thanks

David

[Brianmoooore]

It looks like you have some kind of early sensor with different, more old fashioned connectors!
Diff sensor can fail, but is easy to test. It's simply a switch that can be tested with a continuity (resistance) meter, that switches on and off several times per revolution of one of the wheels. (Can't remember which, so turn both.)
There certainly doesn't appear to be anything wrong with your diff connectors, but the wire still could have failed internally, anywhere up to 300mm from the plug.

[95-540iLE]

Looking at realoem, there appeared to be a change in speedo sensor in 9/1987.

I might solder new wires into the connectors and see if that makes a difference.

Thanks for your assistance.

David

[95-540iLE]

Checked the first 35cm of the wires using a test light today and both wires freely and consistently conducted current - which would suggest to me my problem isn't the wires.

Loks like I need to order a new sensor and try that! Is the new type of sensor a straight swap for the older type?

Thanks.

David

[Brianmoooore]

Have you tested the sensor?

[95-540iLE]

No, I dont have a continuity meter. I am getting a price for both sensors and if not too much, thought I would try a new one as it can't hurt.

Appreciate any other suggestions though!

[Brianmoooore]

Appreciate any other suggestions though!

Buy a £5 test meter!

[95-540iLE]

Will - swapped over the complete clocks. But first tried the complete new cluster and the same result as for the Hartge cluster.

[95-540iLE]

OK, tested the sensor using a multi-meter today. Hooked the connectors of the meter up to the ends of the wires I had cut off and turned one of the wheels (as it has an lsd, both turned).

The result was as suggested by Brianmoore - a pulse type of reading a few times each wheel.

So on the basis of that, both the sensor and wire seemed ok.

Given that, I soldered the wire back on and gave it a test drive, thinking the problem must be the clocks end, even though I have changed clusters. And what do you know, it all works perfectly!

Here's hoping it stays that way!

Thanks for the help guys.

Regards
David