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Help with dash illumination 1988 M5

Posted: Dec 03, 2023 4:45 PM
by York
Can someone please share information on the lighted instruments/ controls on dash. Color code for any would help.
What got this started is my headlight switch is not illuminated and I thought it would be.
My 1972 bmw 2002 headlight switch is not but, I thought by 1988 they would be.
I have a wire diagram and the search begins this week.

Re: Help with dash illumination 1988 M5

Posted: Dec 04, 2023 10:48 AM
by Blue Shadow
www.e38.org/e28 middle of the left column, Electrical Troubleshooting Manual (ETM) has all that info for you.

Re: Help with dash illumination 1988 M5

Posted: Dec 04, 2023 10:54 AM
by BMWCCA2
Couldn't be something as simple as a bulb, could it?
You did check that, right? :laugh:

Re: Help with dash illumination 1988 M5

Posted: Dec 04, 2023 1:04 PM
by Shawn D.
The switch assembly is illuminated, in that the three symbols to the right of the lever light up, but the lever itself does not light up. If the former isn't lit, start by changing the bulb as BMWCCA2 suggested. If you're trying to "fix" the latter, there's nothing to fix.

Re: Help with dash illumination 1988 M5

Posted: Dec 04, 2023 9:04 PM
by York
foxy67 wrote: Dec 04, 2023 10:20 AM Check the headlight switch wiring and connections using the wire diagram to identify any issues, ensuring proper illumination.
Thank you

Re: Help with dash illumination 1988 M5

Posted: Dec 04, 2023 9:06 PM
by York
BMWCCA2 wrote: Dec 04, 2023 10:54 AM Couldn't be something as simple as a bulb, could it?
You did check that, right? :laugh:
How would I know?
I’m still trying to understand which items have light bulbs
My headlights have none , my ac does

Re: Help with dash illumination 1988 M5

Posted: Dec 04, 2023 9:08 PM
by York
Shawn D. wrote: Dec 04, 2023 1:04 PM The switch assembly is illuminated, in that the three symbols to the right of the lever light up, but the lever itself does not light up. If the former isn't lit, start by changing the bulb as BMWCCA2 suggested. If you're trying to "fix" the latter, there's nothing to fix.
I don’t even know which are supposed to have lights
But, thanks for taking the time to reply

Re: Help with dash illumination 1988 M5

Posted: Dec 05, 2023 12:39 PM
by Shawn D.
York wrote: Dec 04, 2023 9:08 PM I don’t even know which are supposed to have lights
There's a single bulb (which is why I phrased it as "the bulb") that lights the right side of the headlight switch assembly. To clarify, were you only asking about the headlight switch, or the entirety of what's supposed to light up on/around the dash?

You can also look on RealOEM.com, BTW.

Re: Help with dash illumination 1988 M5

Posted: Dec 05, 2023 4:48 PM
by York
Shawn D. wrote: Dec 05, 2023 12:39 PM
York wrote: Dec 04, 2023 9:08 PM I don’t even know which are supposed to have lights
There's a single bulb (which is why I phrased it as "the bulb") that lights the right side of the headlight switch assembly. To clarify, were you only asking about the headlight switch, or the entirety of what's supposed to light up on/around the dash?

You can also look on RealOEM.com, BTW.
I’m trying to understand what is illuminated in the
Entire dash , not just the headlights.
I looked at a old sales brochure but, they don’t
List each and every item that has lighting.
Is there such a list
And by the way, thanks for taking the time to help

Re: Help with dash illumination 1988 M5

Posted: Dec 05, 2023 8:03 PM
by Shawn D.
York wrote: Dec 05, 2023 4:48 PM I looked at a old sales brochure but, they don’t
List each and every item that has lighting.
Is there such a list
And by the way, thanks for taking the time to help
You're welcome.

Sales brochures are a pretty terrible way of figuring out stuff like this.

There's no list, but here's what's lit and how many bulbs:

- headlight switch, one bulb
- fog light switch, one bulb
- instruments, two bulbs
- OBC, two bulbs (in one assembly)
- radio (lit internally by ?? bulbs)
- HVAC, lit by one bulb for each knob and one bulb for each slider, plus one bulb in the AC button
- lighter/ashtray, one bulb attached to the side of the lighter assembly
- window switches, two bulbs each ('87 and '88 only)

Re: Help with dash illumination 1988 M5

Posted: Dec 06, 2023 10:21 AM
by Blue Shadow
Shawn D. wrote: Dec 05, 2023 8:03 PM
There's no list, but here's what's lit and how many bulbs:
All are shown in their circuits in the ETM linked above.

Re: Help with dash illumination 1988 M5

Posted: Dec 08, 2023 2:52 PM
by York
If all the illumination bulbs are the same , could you suggest a source and are there led bulbs which would be better ?

Re: Help with dash illumination 1988 M5

Posted: Dec 08, 2023 9:34 PM
by RetiredDoc
I posted this more than 10 years ago but can’t find my list. So to get you started from memory the three HVAC slider controls, the headlight switch, the OBC display itself and the OBC buttons (different bulbs), the radio (I believe there are 2 bulbs since one side of my radio display has gone dark), snowflake AC button when engaged, all of the power window switches and sunroof switch (this varies as some models came with unlighted window switches), the instrument panel by bulbs above it in the cluster, both the temp and fan speed knobs, hazard light switch, and rear window defrost switch. The M5 has heated seats so those buttons are also illuminated.

Re: Help with dash illumination 1988 M5

Posted: Dec 08, 2023 10:39 PM
by Shawn D.
York wrote: Dec 08, 2023 2:52 PM If all the illumination bulbs are the same ,
You'll have to look up the P/Ns on RealOEM to determine that.
York wrote: Dec 08, 2023 2:52 PM are there led bulbs which would be better ?
No, because LEDs do not dim linearly as incandescents do. There are probably some that will function, but will not have the same adjustability.

Re: Help with dash illumination 1988 M5

Posted: Dec 08, 2023 11:31 PM
by York
Shawn D. wrote: Dec 08, 2023 10:39 PM
York wrote: Dec 08, 2023 2:52 PM If all the illumination bulbs are the same ,
You'll have to look up the P/Ns on RealOEM to determine that.
York wrote: Dec 08, 2023 2:52 PM are there led bulbs which would be better ?
No, because LEDs do not dim linearly as incandescents do. There are probably some that will function, but will not have the same adjustability.
How do I dim ?

Re: Help with dash illumination 1988 M5

Posted: Dec 09, 2023 11:36 AM
by Blue Shadow
York wrote: Dec 08, 2023 11:31 PM

How do I dim ?
The LEDs don't really dim. On or off.
Incandescent light bulbs dim with the wheel on the headlamp switch.

Re: Help with dash illumination 1988 M5

Posted: Dec 09, 2023 1:32 PM
by Shawn D.
York wrote: Dec 08, 2023 11:31 PM How do I dim ?
You dim LEDs by implementing pulse width modulation (PWM). Doing so would require a rework of the dimming circuit. If you want to do that, you'll have to figure it out yourself.

FWIW, this is the only off-the-shelf interface I know of, but it only handles six of their gauges. How many LEDs that entails is something I don't know. You'll have to research that.

Re: Help with dash illumination 1988 M5

Posted: Dec 10, 2023 9:24 PM
by York
When I asked, how do I dim ? I meant generally speaking
Not led’s

Re: Help with dash illumination 1988 M5

Posted: Dec 10, 2023 10:24 PM
by Shawn D.
Just look at your light switch. It's pretty obvious.

Re: Help with dash illumination 1988 M5

Posted: Dec 12, 2023 4:46 PM
by Blue Shadow
York wrote: Dec 10, 2023 9:24 PM When I asked, how do I dim ? I meant generally speaking
Not led’s
I answered that two posts above your post asking how to dim.

Re: Help with dash illumination 1988 M5

Posted: Dec 13, 2023 1:33 PM
by Philo
I love it when Shawn weighs in on the conversation. So detailed, love it ! The dash lighting issue is something I need to look into as well. My RPM side light is out, sliders aren't working, some window button lights are out.

good kick in the butt thread..

Re: Help with dash illumination 1988 M5

Posted: Dec 13, 2023 4:05 PM
by Mike W.
Philo wrote: Dec 13, 2023 1:33 PM I love it when Shawn weighs in on the conversation. So detailed, love it ! The dash lighting issue is something I need to look into as well. My RPM side light is out, sliders aren't working, some window button lights are out.

good kick in the butt thread..
I thought the window switch bulbs were NLA. Back when they were common in the yards you could go thru and grab a couple if you had one burnt out, but that was then and this is now. Might be available or a substitute, there's so much more stuff online than there was in the early 2000's.

Re: Help with dash illumination 1988 M5

Posted: Dec 13, 2023 5:29 PM
by DavidE9
FWIW, I just bought a few replacement window switches off eBay. Complete garbage.

https://www.ebay.com/itm/134441538272

I tried to fix my switches, but I couldn't get them open:

viewtopic.php?t=93466