vss issue.. no mph with scan tool

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Jul 11, 2012 | 01:55 AM

nesluopetan

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From: Utah

vss issue.. no mph with scan tool

I just swapped a 6.0/4L60E in a 72 chevelle and I'm having a problem.. I can't get the car to shift and I heard if the ECU does not read MPH properly it will cause this to happen. Well, My OBD II autoscanner has a live feed mode which reads out MPH and sure enough it stays at 0 mph while in gear and driving..

I checked the ecu right at Pin 21 on the red connector ( PPL/WHT ) VSS Input and it has continuity from the VSS plug itself, so why in the world would the ECU not read any MPH? I can understand my gauges not showing mph since I haven't calibrated my gauges yet with the VSS output wire but I don't understand why the ECU doesn't read the MPH since the VSS input wires are connected properly in the harness with the proper gear ratio and tire size flashed in.

Any suggestions? I need to get the MPH working next and then see if it fixes the no shift issue, But regardless, if it doesn't fix the shift issue I still need to get the MPH readout working so the ECU knows when the car is moving.

Thanks!

Jul 11, 2012 | 03:14 AM

garys 68

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From: Camdenton, MO

You should be able to read AC voltage off the 2 wires from the vss. If not, bad vss, wiring, or too far from reluctor.
You can also do a quick check by reading the resistance in the two vss wires at the ecu.

Last edited by garys 68; Jul 11, 2012 at 06:08 AM.

Jul 11, 2012 | 07:50 AM

Old Geezer

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From: GA, USA

What gauges are you using?

Jul 11, 2012 | 09:54 PM

ALTRDTA

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From: Utah

Quote:

Originally Posted by Old Geezer

What gauges are you using?

He's using autometer Gauges. But like was said. It's not an issue of the guages not reading. He's having issues of no MPH in the PCM readout to his tuner...

Jul 12, 2012 | 07:21 AM

rsz288

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Are you using stock ECM and TCM? Some GM platforms take the VSS from the ABS system. Especially trucks and G8's.

Jul 12, 2012 | 07:47 AM

ls1nova71

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From: Liberty, MO

A 6.0 would have originally came with a 4l80e, what harness are you using? Did you mod it for the 4l60e? Did you have the 4l60e trans segment swapped in the tune? Also you say you checked continuity on one vss wire, did you check the other one too?

Last edited by ls1nova71; Jul 12, 2012 at 07:52 AM.