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9fourteen 9fourteen is offline
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Join Date: Nov 2002
Location: Cincinnati, OH
Posts: 166
Garage
Speed/Reference Sensor Testing Help

I bought my 944 about 2 weeks ago. It ran great for about a week and then I got a "no start". Been trying to troubleshoot it over the last week. DME relay tested up fine and jumping it didn't fix it. I get no spark and coil tested fine. According to the troubleshooting procedures from Clarks Garage I am down it either being the Speed or Reference sensor or the DME computer itself. I got no bounce on the tach so I am guessing it is the sensors.

I have followed the procedure to test both the speed and reference sensors and I get nothing on both sensors. The resistance test shows 0 on all leads. I grabbed an oscilloscope from work and it shows nothing either. I am thinking I got to be doing something wrong. I wouldn't think both sensors would fail at the exact same time and both be completely dead.

Here are some pictures of where I am testing and how I got the oscilloscope hooked up. Am I testing the correct leads? I should be connected to 8 and 27 on the DG. (The DG is on top and I did trace everything and it is all correct on the bracket). I am no expert on the oscilloscope, what should the settings be? I think I have it set for DC. I didn't try AC but I remember the speed sensors on my van put out AC volts. Could that be my problem.






Any help would be appreciated, thanks.
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Running Cars
06 Boxster S, 85 944, 83 928S
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74 914, 74 911, 72 914, 66 911, 65 912
Old 09-07-2013, 06:03 PM
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