Speedometer sensor testing 5000 QT

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Dec 1, 2009 | 10:10 PM

Supradjza80

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Speedometer sensor testing 5000 QT

Hey guys,

I purchased my 87 turbo quattro 5000 with an inoperative speedo. After using the bentley I have determined that it is either the speedo sensor or the IC that is the problem. I have tested my speedo sensor and show that I get no pulsing 8V's from pins 2-3 when 12v is applied across 1-3 and the sensor is spun slowly clockwise. Due to this I have ordered replacements from force 5 and received two new sensors, both sensor also produce no pulsing 8V signal when doing the above test procedure.

Due to this I am lead to beleive my test system may be flawed or I am very unlucky and have 3 bad sensors. Has anybody done this test before and had trouble using a DMM to run the pulsing test? I think my meter responds fast enough that the test should be accurate but want to make sure I am not doing something incorrectly.

I am contemplating bringing the sensors to an electronics place to have someone use an Osciloscope on the sensor to be sure that they are all bad.

Thanks,
Dave

Dec 2, 2009 | 04:35 AM

5000CDQturbo

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From: Ottawa, Canada

welcome Dave to the forum !!

Inoperative Speedo is usually a cluster problem. I'm sorry I couldn't be of more help . superdave

Dec 2, 2009 | 06:31 AM

hdmyers

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my speedo is intermittent. yanking IC tonite to solder things up and make right.

Dec 2, 2009 | 07:55 AM

Supradjza80

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Quote:

Originally Posted by 5000CDQturbo

welcome Dave to the forum !!

Inoperative Speedo is usually a cluster problem. I'm sorry I couldn't be of more help . superdave

Thanks for the response and the welcome, I understand that clusters are a problem but I have never tested any of my 3 speedo sensors and had them pass the Bentley test. Has anyone done it with a DMM and had the test work? Or do I need an Oscilloscope to see the pulses?

Dec 2, 2009 | 12:28 PM

hdmyers

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i thought that you just measure impedance on the suckers to see if they are good or not.

Dec 2, 2009 | 02:55 PM

Supradjza80

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Quote:

Originally Posted by hdmyers

i thought that you just measure impedance on the suckers to see if they are good or not.

Well the manual says to test for voltage while spinning it slowly.

Dave

Dec 4, 2009 | 07:42 AM

hdmyers

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I can take a look. I can't get my fricken unit unbolted from my car. (one of the hex's mangled by my lack of patience!). Would be kewl to test regardless. I'll let you know.