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  #16 (permalink)  
Old 07-31-2011, 03:53 PM
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Did some more testing. I monitored the VSS signal where it goes into the VSS Buffer, and it is erratic. Drops to zero the instant I let off the gas even though I wasn't slowing down. That shouldn't happen.

Next to run two temporary wires to VSS and see if that helps.

However, the consistency of what happens doesn't look like broken wires that make intermittent contact. It sure seems to point back to that reluctor ring in the TC slipping somehow.
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  #17 (permalink)  
Old 07-31-2011, 07:49 PM
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Quote:
Originally Posted by Argess
Did some more testing. I monitored the VSS signal where it goes into the VSS Buffer, and it is erratic. Drops to zero the instant I let off the gas even though I wasn't slowing down. That shouldn't happen.

Next to run two temporary wires to VSS and see if that helps.

However, the consistency of what happens doesn't look like broken wires that make intermittent contact. It sure seems to point back to that reluctor ring in the TC slipping somehow.
or the chance that you bought a bad v.s.s. cant rule that out either.
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  #18 (permalink)  
Old 07-31-2011, 08:13 PM
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Also keep in mind if the VSS is not orientated correctly as it faces the reluctor wheel , readings will be erratic
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Old 08-01-2011, 07:34 AM
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Yes, the replacement VSS could be the problem. When I monitored the VSS output, I did it with the VSS buffer connected. Since then, I tried monitoring it with the VSS BUffer disconnected and although the VSS sensor output was lower, it did seem to follow the vehicle speed properly.

I don't think this particular VSS sensor is dependent on orientation as it screws in. No flange with a bolt, like some of them.

I managed to jumper pins A and B on the OBD connector and got two codes. The first was 12, telling me the PCM passed it's diagnostic check, and the second is code 27, which appears to have something to do with the transmission. I"m still researching what code 27 means, but am not getting anywhere as of yet.
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Old 08-01-2011, 08:23 AM
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I found this:

27 quad-driver module (computer) 2nd gear circuit
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Old 08-01-2011, 02:48 PM
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Thank-you. That's pretty much all I found too.

So... I disconnected the battery and stepped on the brake pedal to discharge the PCM and clear the codes. It now shifts normally, but the speedometer still drops when I ease off of the throttle, and then comes back up when I increase the throttle. My speedometer is acting like a throttle position indicator!

No doubt the VSS system is still the culprit for that, and the shifting problem might come back if I don't fix it.
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  #22 (permalink)  
Old 08-01-2011, 03:59 PM
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Have you check for a rotted off ground somewhere. It doesnt make sense that throttle position is affecting the spedo.
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Old 08-01-2011, 05:05 PM
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Quote:
Originally Posted by T-bucket23
Have you check for a rotted off ground somewhere. It doesnt make sense that throttle position is affecting the spedo.
You are reading my mind. That's next. It did occur to me, that if something like the throttle position sensor, and the VSS buffer share the same ground, and it's a bad connection, one might affect the other.

Not sure where to look, but I'm going to look. Might even put an extra GND wire to VSS buffer ground to see if it helps.

By the way, I know this isn't your typical hot-rodding question/thread, but I really appreciate all the help and suggestions. Thank-you all.
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Old 08-05-2011, 03:22 PM
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It's been raining a lot, so not much done, but some progress today.

The Code 27 did eventually come back along with shifting problems. I tried an extra ground to the VSS Buffer with no luck.

So, I reset the computer again, wiggled all grounds on the engine, pulled a few engine plugs and re-inserted them, ensured the heater fan, radio and cruise control were all OFF, and the test drive went perfectly. Better than last time as even the speedometer worked correctly.

Will drive it some more and if it stays OK, then I'll start turning on the accessories one at a time and see if the problem comes back. If it does, then I will check power and grounds for the offending system.
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