E34 speedometer stopped working in cold, kinda.

[632 Regal]

On my way to work, I would think I would have noticed it before the main road but the speedometer wasn't working. The odometer was working though WTF? I noticed when I was going appx 50ish the speedometer was up to about 10 MPH. Getting signal but sluggish. Hoping it was due to the cold even though I ran the car and heat 15 minutes before I left. It was about 26 F and the car was warm inside, engine temp half way so fully warm. Stopped off and shut down and restarted no deals. 2500 rpm = 45 mph (3:64 gears).

After work everything was fine again. Never experienced this before so figured I would post just for my own reference as I usually do lol.

[shogun]

Which cluster back plate do you have? Grey, blue or white? The oldest ones = gray needs new capacitors http://www.exx.se/maintenance/instrument_cluster_e34/index.shtml
And check the speed sensor and wires on the diff http://www.bmwe34.net/E34main/Maintenance/Electrical/speed_sensor.htm

on my website is another fix under fixes>>instruments>>>Replace blown resistor in speedometer: -- symptoms, write up and photos

[632 Regal]

No clue, it works after the car is warm, like after I get to the job and travel out again. I have a 540 for parts can I just change the speedo unit?

[632 Regal]

Same scenario again. Don't like cold this year.

[shogun]

In case the tank volume is the same, you can change the cluster, otherwise the cluster would show a wrong tank volume, as this is in the cluster chip programmed. In case the backplate color of the cluster is the same, you can even swop the 'chip' from one to the other cluster, so you would have even the same data shown like VIN, total mileage etc.
There are 3 cluster versions, oldest one is grey backplate, that does not have the chip in the back of the cluster but in the wire loom to the cluster, white and blue backplate versions have the chip in the backside. Code chips of white and blue cluster are not interchangeable, as they have different sizes.
the grey backplate one can be replaced by blue or white. Grey backplate cannot replace white and blue. All explained here http://www.exx.se/maintenance/instrument_cluster_e34/index.shtml
But for a test you can use the cluster from the 540 anyway.

[winfred]

if the odo is accurate its likely a mechanical issue with the speedo as they run off the same signal

[632 Regal]

if the odo is accurate its likely a mechanical issue with the speedo as they run off the same signal

Odometer is dead nuts, works fine. Just the speedo seems like it's packed with grease when sub 35 degrees, wont go above 10mph. Above that temperature it's fine' also after sitting it works fine. So I'm leaning on a speedo cluster issue. We don't have much cold here in TN but it does bother me when traveling next to the feds in the morning not having a clue where I'm at.

[shogun]

just unlock the OBC: 8 Current speed (km/h)

Getting into the Test Codes:
============================
Push OBC buttons 1000 and 10 together. You will see the word Test. By pressing a combination of the 10 and 1's you can enter Test Codes from 1 to 21. After entering the number press R/S and you will get a continuous display of the test function. To cancel, just press any of the OBC function keys.

List of Available Tests:
========================
Test Number Description
1 Display Test (all LCDs and LEDs activate)
2 Current Consumption in litres / 100 km
3 Current Consumption in litres / hour
4 Average consumption (used in calculating range)
5 Current Range
6 Not used (this function is active on some, but not sure of the purpose)
7 Fuel Remaining in Tank (litres)
8 Current speed (km/h)
9 System Voltage at Terminal R
10 Country / Language
11 Units / am.pm
12 Average speed (km/h) for calculating ETA
13 ETA
14 Date of software / mask of OBC
15 Production Diagnosis
16 Production Diagnosis
17 Display Vehicle Specific Data
18 Alarm Changeover (continuous vs. intermittent)
19 Lock / Unlock all functions (Sum of month and date to unlock or lock)
20 Correction Factor for OBC Fuel Consumption
21 Reset all defect codes, date and time

!!! You need to unlock the OBC before you can change the settings. !!!

How to lock and unlock the OBC:
===============================
To unlock the OBC, first press the date key, and add the month and day together. So, if the date is displayed as "0704", the result is "11".

Go to test 19 by pressing the 1000 and 10 buttons together, and then typing in the test number (19)·

You will see the word "LOCK" displayed. Type in the result from step 1 above, and press S/R·

If you display test 19 again, it will now display "FREI", indicating the system is now unlocked.

To lock the system again, go to test 19, and press the little button on the top left hand corner of the OBC (F/C).

How to correct your fuel consumption readout:
=============================================
If your car is anything like mine, the fuel consumption readout will be way out. But it can be adjusted! First, you need to measure your fuel consumption as accurately as possible, by filling up the tank, driving until nearly empty, filling again, and figuring out your fuel consumption, in either litres / 100 kms, or MPG. At this point, also note what the fuel consumption as reported by the OBC is. You need both figures to make the adjustment. Once you have that accurate figure, follow the following procedure:

Unlock the OBC as described above.

Go to test 20.

This is the existing fuel consumption constant used in the calculation.

Find the ratio between the old consumption reading, and the actual consumption reading:

For litres per 100kms, this is the actual consumption divided by the reported consumption.

For MPG, it is the opposite. Ie. It is the reported conumption divided by the actual consumption.

Now multiply that ratio with the existing fuel consumption constant, the result is the new constant.

Simply type in the new constant, and press S/R NOTE: Some claim that for some reason, if you don't drive your car for a day or two, the constant will reset back to 1000.

[632 Regal]

Thanks, I couldn't find my copy anywhere.