Speedometer / Odometer relationship

E28 technical advice asked and given! Troubleshooting, modifications and more.
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skonka
Posts: 9
Joined: Jun 08, 2020 9:12 AM
Location: Wilmington, DE

Speedometer / Odometer relationship

Post by skonka »

Greetings. New to the forum. Been an E28 fan for a long time but just recently bought a 535i as an extra vehicle that will get light daily duty. Sorting out some of the problems including inop speedo and odometer. I've got the cluster out and now have gears as well as an SI board on order. (Batteries spewed on board a bit and main small odometer motor has missing teeth). I am curious though, can anyone share the relationship between the inop speedo versus odometer? I've searched quite a bit and haven't come up with anything. Can/Will speedo work if odometer is inop? I've got power and grounds at the proper connector positions. Just wondering if I'm in for a repair on the speedo after the other parts have been installed. FWIW, tach, fuel and temp are all working. OBC not, but will get to that next. Thanks for any help!
Blue Shadow
Posts: 10195
Joined: Feb 12, 2006 12:00 PM
Location: SE PA

Re: Speedometer / Odometer relationship

Post by Blue Shadow »

Is the obc showing info without the backlight? I have some LED converted lamp boards available. Drive by for one if you want, West Chester. I sell em with core charge/board swap so I can keep the boards available.

The speedo will work and the odo will stop when the gears die. Common. Gears get the wheels turning again.

Both out, verify the pulses from the diff output.

www.e38.org/e28 has the electrical manuals middle of the left column should show the speedo wiring.
skonka
Posts: 9
Joined: Jun 08, 2020 9:12 AM
Location: Wilmington, DE

Re: Speedometer / Odometer relationship

Post by skonka »

Thanks Blue Shadow, I'll probably take you up on that. Might take me some time but will be in touch. The OBC shows nothing ATM. I plan to dig into that when I pull the cluster back out to install the parts I just ordered. Hope to go through inspection this week. I'll check the VSS sensor next, plan to change rear lube anyway and then wiring if still having trouble. Appreciate the info.
Mike W.
Posts: 26872
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Speedometer / Odometer relationship

Post by Mike W. »

If the SI board is bad it can render any and all of the gauges inoperative.
skonka
Posts: 9
Joined: Jun 08, 2020 9:12 AM
Location: Wilmington, DE

Re: Speedometer / Odometer relationship

Post by skonka »

Thanks for the info!
skonka
Posts: 9
Joined: Jun 08, 2020 9:12 AM
Location: Wilmington, DE

Re: Speedometer / Odometer relationship

Post by skonka »

Installed new gears and Programa SI board and all cluster functions work again!
Thanks for all of the help.
Next, the drive light is out on the gear selection indicator. Appears the bulbs are soldered onto the PC board. Any replacement options out there?
demetk
Posts: 8431
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: Speedometer / Odometer relationship

Post by demetk »

skonka wrote: Oct 10, 2021 12:02 PM INext, the drive light is out on the gear selection indicator. Appears the bulbs are soldered onto the PC board. Any replacement options out there?
Look for Wire Terminal Base bulbs. Like maybe these https://www.bulbs.com/product/2182D
Blue Shadow
Posts: 10195
Joined: Feb 12, 2006 12:00 PM
Location: SE PA

Re: Speedometer / Odometer relationship

Post by Blue Shadow »

I have a clusterfuch here and some have the at light bars. You're welcome to a few bulbs and since the soldering iron is out on the bench (always, I mess with vintage audio crap) we can put one in while you wait.

A clusterfuch is 6 gauge clusters in various states of build or disassembly.
skonka
Posts: 9
Joined: Jun 08, 2020 9:12 AM
Location: Wilmington, DE

Re: Speedometer / Odometer relationship

Post by skonka »

Blue Shadow wrote: Oct 11, 2021 2:35 AM A clusterfuch is 6 gauge clusters in various states of build or disassembly.
Thanks for the laugh!
Tell me more about your OBC solution Blue Shadow, if you prefer to take this to PM, feel free, or respond here. Up to you.
Looks like my OBC is working but you can barely see the display. Bulb in back is good. Does your offering cure that?
Perhaps we can kill two birds with one visit....
Blue Shadow
Posts: 10195
Joined: Feb 12, 2006 12:00 PM
Location: SE PA

Re: Speedometer / Odometer relationship

Post by Blue Shadow »

the white square on the side of the OBC is a light bar. This light bar is what illuminates the display and runs a pair of lamps in series. I think I have one with incandescent lamps, would have to check but I have a few already rebuilt with LEDs and have a handful of LEDs and half a handful of the voltage dropping resistors to rebuild a few more units.

Part #3 https://www.realoem.com/bmw/enUS/showpa ... Id=62_0176
Bulb 4 is just the backlight for the input pad.

These used to sell for about 30 from BMW but they are now over 100. They want us to reuse the old housing and rebuild them at that price.

I exchange em for about 25 plus fees, shipping both ways and such, depending. An online retailer has em for 44 now less 10% used to be 30 IIRC. I should reconsider my pricing. Electronic parts are going up in price if they are available. I find quite a few parts are going out of stock with long lead times or being discontinued in the vintage audio arena.
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