Chevrolet Corvette:

VSS reading 43mph with vehicle running/not running

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# 1  5/7/2009 8:04 PM

New member
Registered: 5/7/2009
Posts: 1

VSS reading 43mph with vehicle running/not running

2005 Corvette, manual trans. VSS problem. No vehicle speed detected. With Snap-On Modis scanner reads 43 mph vehicle speed at all times, with key on/ engine off/vehicle stopped. Also engine running/ vehicle moving at any speed. Have checked continuity of each wire from VSS to C-3 plug, pins #44-45. No problem. Symptom is a low/ fluctuating low idle/ engine dying when rolling up to a stop. RPM's will drop to 500 rpm then come back up to +- 1000 rpm. Sometimes will drop then drop off and engine quits. Or will recover and sit and idle nicely. Will restart every time no problem. Codes 502-503.

Additional info: 1954 OHMS between hi signal and lo signal (range 988-2200). Measured at C-3 plug pins and with VSS connected.

Last edited by restoreclassics (5/7/2009 9:07 PM)



# 2  5/8/2009 1:47 AM

Registered: 9/27/2008
Posts: 1282

Re: VSS reading 43mph with vehicle running/not running


You're on the right track. Do you have a copy of the testing description for the two VSS codes? While checking continuity of the high and low circuits between the VSS and PCM, also check them for shorts to ground, shorts to voltage and shorts to each other. You're showing the correct resistance between the high and low terminals on the sensor, but be sure and check the resistance from each terminal to ground also. The sensor could be shorted to its mounting bracket. The next step is an AC voltage test followed by removal and inspection of the VSS, the rotor, and the air gap. If the VSS and the two circuits are 100%, that leaves the PCM, or some oddball problem like a poor ground. Not positive, but the 43mph reading on the scanner may be a default number when there's no signal or a break in the circuit.

Hope that helps.
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