Speed Pulse

[Only me]

Hi folks,

Anyone got any ideas how I can check out if the speed pulse connection in my w202 c200 (1998) is working/ connected at the instrument panel end?
I have a connection to pin 1 on my Din A connector - green / violet(?) which I believe should be correct.

I have just put in a Blaupunkt head unit with auto volume increase with road speed (and yes, it is enabled in the menu!), but the volume increase must be pretty subtle as I am not sure if it is doing anything at all!!

Any ideas??

Thanks

GB

 

[fred_raven]

hi - i hae a becker head unit - when i set mine it didnt seem to be doing much - but the settings work in reverse of what i thought normal , ie for more change in level u need a low number .

may just be worth trying with settings on min and max just to be sure!

 

[Only me]

Thanks Fred - but no apparent difference on min or max setting!

From other posts on here, that green / purple wire at pin 1 should be the speed pulse wire - Blaupunkt support guy confirmed auto sound increase should be set to max for largest increase.

Does not appear to be doing anything - or if it is, it is a very subtle volume increase when set on Max!

Really looking for someone who can give me a definative method of testing pulse wire operation.
Opinions on here seem to vary.

Thanks again

GB

 

[Alfie]

Thanks Fred - but no apparent difference on min or max setting!

From other posts on here, that green / purple wire at pin 1 should be the speed pulse wire - Blaupunkt support guy confirmed auto sound increase should be set to max for largest increase.

Does not appear to be doing anything - or if it is, it is a very subtle volume increase when set on Max!

Really looking for someone who can give me a definative method of testing pulse wire operation.
Opinions on here seem to vary.

Thanks again

GB

If you have access to a COMAND unit (A163 variety) then you could plug that in, with an antennae resting on the dash and then we would see if the speed pulse is working or not. If you fancy a visit to Woking, I'm happy to test this for you.

 

[Only me]

Thank for offer Alfie - but I am in North East of Scotland!

Seems to be a fair bit of confusion on speed pulse generation on W202s in their various guises.

GB

I'll keep working on it - it won't beat me!!!!

 

[richard]

Stick a multimeter on it (set to DC volts), and roll car forward slowly, should switch between 0 and 12v, 48 times per wheel revolution, or if you are driving along, should look like somewhere between 4.5 and 9 volts (i can't remember how long the speed pulses are)

R

 

[LeperKing]

I used an LED, it's very clear if its working or not.

LK

 

[Only me]

Thanks Leperking and richard - I'll give both these a try - I have both a multimeter and some 12v leds lying around.

Let you know how I get on

GB

 

[Only me]

Well - I found the problem!!

After trying unsuccessfully to get any voltage reading from the green/purple wire behind my head unit using a multimeter (and a led), I had come to the conclusion that there must be something disconnected at the other end of the wire.

So - last night I decided to investigate further. I started by unwrapping a few turns of non OEM insulation tape from the wiring cable about 50mm from the dim plug - Guess what I found.

Yep, two separate ends of a green / purple wire!!!!!

A bit of solder and some heat shrink sleeving and all is again well with the world.

Thanks for all the suggestions folks - next time I'll look for the more obvious first before suspecting an alien conspiracy!

GB