Inoperative Speedometer

[kombikat]

I have checked the differential connection plug and wire and there is no obvious sign of a broken or deteriorated cable.
Is there any way of using a multimeter to test if the circuit is unbroken?
Assuming that the wiring is good it seems that I have to move on to the dash to resolder: which joints are the ones I should be checking / re-making please?
Thanks

[turk]

Check the plug on the diff, and wire etc. then chck the little brass nuts on the back of the cluster are nice and tight... is it just the speedo not working or are the revs out too?

[jimbob29]

help!have lowered my 320i on 35mm lowering springs front and rear!every i drive through buit up area i can hear slight metallic sound from under car i have checked all wheel bearings and replaced flex disc and center support bearing.could it be rotor shield rubbing cant hear anything when jacket up with wheels spining.also had few passengers in rear few days ago next day i went to work ther is slight knock in boot area through 1st n 2nd does not knock any other time.thanx

[Brianmoooore]

help!have lowered my 320i on 35mm lowering springs front and rear!every i drive through buit up area i can hear slight metallic sound from under car i have checked all wheel bearings and replaced flex disc and center support bearing.could it be rotor shield rubbing cant hear anything when jacket up with wheels spining.also had few passengers in rear few days ago next day i went to work ther is slight knock in boot area through 1st n 2nd does not knock any other time.thanx

Please repost this as a new topic, not on someone else's thread.

[Brianmoooore]

I have checked the differential connection plug and wire and there is no obvious sign of a broken or deteriorated cable.

There normally isn't! The copper breaks internally because vibration has made it brittle. Pull each individual wire gently, and if it stretches, you've found the break.
Replace the last 300mm of wire, complete with plug. A repair will only be temporary because of the changed state of the copper.
The wires put in an appearance at the plug and socket at the RH side of the rear seat pan, under the seat cushion.

[Dunelm2K]

Similarly to the original post on this thread, the speedometer on my 325i has taken on a Jekyll and Hyde split personality. When accelerating, or driving normally, the needle wobbles like crazy between 0 and whatever speed one is doing. However, as soon as I take my foot off the accelerator, the needle sits calmly and indicates the correct speed. It's a mystery I am trying to solve.

All other instruments are working fine, except for the MPG meter and service indicator lights (neither of which I ever used anyway). The rev counter, fuel gauge and temperature gauge all behave impeccably (touch wood) and the mileometer is aso working fine.

Any ideas???

[Brianmoooore]

As above! Diff. is twisting about during acceleration and braking, making the wire make and break contact.

[Dunelm2K]

That makes a lot of sense. Thanks

[johnl320]

I'll vouch for Brians diagnosis, I had exactly the same problem with the speedo, no obvious breaks, renewed approx 300mm of the wire leading to the diff connection and problem gone.
What I will add is the the wire replacement needs to be done properly, with soldering iron and if possible heat shrink.

[TPS]

Same here, I've had the same fault, renewed the wiring, job done!

[kombikat]

Thanks for all the help - I'm joining the car in France tomorrow with the recommended bits & I'll report how I get on!
Gordon

[Bfab]

Hello folks

I seem to have the same problem with my speedo. Ive had a quick glance at the connection on diff and seems ok. But I noticed a dodgey connection on a cable which goes to a connector next to the drivers side engine mount just above the oil pan. Any ideas what this is for

[Bfab]

Hello folks

I seem to have the same problem with my speedo. Ive had a quick glance at the connection on diff and seems ok. But I noticed a dodgey connection on a cable which goes to a connector next to the drivers side engine mount just above the oil pan. Any ideas what this is for

I cant seem to attach a pic for guidance.

[Brianmoooore]

Since you haven't told us what you have under the bonnet of your E30, then no, I can't.

[Bfab]

Sorry. Its a 320 M20 engine.

[Brianmoooore]

If the connector is a round one, and is directly under the centre of the inlet manifold, then this is a well known M20 trouble spot. Water gets into the rubber boot under the lower half of the plug and socket, gets trapped, and eventually rots through some of the wires.
The wires in question carry the signals to the injectors (in groups of three) and the signals from the coolant temperature sensors for both the ECU and the gauge.

[PeteE30Tourer]

This is the next job on my 92 325i cab. Now the car is officially back on the road (as of this morning), the drive to work without a working speedo is driving me mad. I have the exact same symptoms as described above - under acceleration the speedo is erratic at the best of times, but on the over-run, it usually calms down to give a stable reading.

I haven't jacked the car up to look at the cabling yet, but I wanted to ask if the connector usually needs to be replaced too and if so, what is the part number? How are the wires connected to the connector on the diff? Screw? Solder? Crimp?

[Brianmoooore]

The outer coloured part of the plug is removable (and available separately from BMW), but the actual buckets of the plug are moulded onto ends of the wires.
IIRC, BMW can supply a repair cable, but a suitable connector with wires that won't be suffering from 'work hardening', can be found connected to the headlamps on a scrap car.

[Bfab]

I have a few pics of the connector. Is there anyway I can send u a pic?

[PeteE30Tourer]

Cant you post them on here?

[Bfab]

Cant seem to post pics. How did u do it?

[monkeyboy1979]

If you pop them on photobucket.com and then use the link code (provided by photobucket) for IMG then it will pop up mate so the text will look like

IMG http://i296.photobucket.com/albums/mm17 ... MG1632.jpg /IMG

[Bfab]

Ok thanks. ill give it a try.

[jimbob29]

my speedo only works when the heating has been on for while or on a really cold morning then stops completely rev counter started sticking?mate of mine said its the soldering on back of speedo contracting and expanding with heat? i checked sensor on diff seems ok i think??why would my engine cut out when removing diff sensor?

[Brianmoooore]

Your mate could be right. The speedo assembly plugs into the main circuit board, and cracks have been known to form where the pins are soldered to the speedo daughter board.
No possible connection between removing the diff sensor and the engine cutting out.

[Bfab]

This is the connecter I was talking about.

<iframe frameborder="0" style="width:150px;" src="http://www.photobox.co.uk/album/767806308"></iframe>

[Bfab]

This is the connecter I was talking about.

<iframe frameborder="0" style="width:150px;" src="http://www.photobox.co.uk/album/767806308"></iframe>

http://www.photobox.co.uk/album/767806308

[Brianmoooore]

Switch for the oil pressure light.

[Bfab]

Ok cheers