[unknown4u]

Today the speedo went down to zero. and after a few seconds the Big ! came up as also the brake light.

I checked the sensor at the lef front wheel. But the sensor gives a signal, still replaced it with another but no result.

I do have 2 questions.
1: Is it always that the speedo has his signal from the front left sensor?
2: I completly checked this forum but could nog find a DIY for diagnoses.

Can somebody help me out?
Thanks.

I have to fix it quick because I must pass the roadtest soon.

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[unknown4u]

I suppose nobody has ever had this kind of problem............. still no reaction at all.

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[jfrahm]

I think it is the LF wheel sensor, there is a thread on it:
*edited*

http://www.968forums.com/index.php?showtopic=8084

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[DaveN]

I was just going to add that there are 2 sensors, one on each wheel. Not sure if Porsche averages both sensors fo rthe speedo or if one does something else.

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[unknown4u]

Just checked the cables and the speedsensors at each wheel.
They ar all in good condition.
Exact the same view on the oscilloscoop.

The 3 grounds from the ABS units are ok as well.

Have to measure now the 12 Volt circuits.

Thats for tommorow.

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[jfrahm]

Did you look for voltage from each wheel sensor at the ABS brain? This can be done with a DMM while driving slowly. Look for AC volts.

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[unknown4u]

voltage and pattern are equal.

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[F355GTS]

Perhaps another problem? Although mine is a RHD and therefore cable routing may well be different I had a problem where my ABS light came on and I lost Alternator charging because the loom had been worn by the clutch mechanism and caused 4 of the wires to ground including the two for ABS and Volts lights.

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[unknown4u]

I found it.

The relais G22 was the gremlin.
I was measuring yesterday at the ABS connector and I had a voltage. And today not......
I opened it and it had a burned smell.
I controled it separte from the car and it was malfunctioning.

Replaced. Problem solved and a happy owner again.

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[jfrahm]

I should have thought of that! Good work. Some of these 'relays' are a gadget with one or more relay stuffed in a relay box. Irritating.

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[Johannvb]

Well done!

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[unknown4u]

I was on a busnisstrip so a late reply. Thanks all for the help!.

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[dougschrank]

its the abs relay!! my reply to a post is up top today! you can order from Pelican parts and get next day for about $20+$80 for the part.

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