'93 B-350 van speedometer intermittent causes overdrive intermittent
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From: Kings Mountain, NC
'93 B-350 van speedometer intermittent causes overdrive intermittent
Recently purchased this '93 van. Transmission is not original, it is a A518 transmission circa 1987 era. Transmission was missing vehicle speed sensor (VSS) adapter from tail of transmission. I found a VSS in a junk yard that matches the three pin connector of my van's harness. I installed that VSS onto the transmission.
THE ISSUE:
Speedometer will work intermittently (almost never works). When the speedometer is working the overdrive works normally, when the speedometer quits (while driving) the overdrive downshifts to 3d gear or won't engage (unless the speedometer is working).
The wiring diagram shows that the wire from the VSS which runs to the PCM splices-off to the speedometer (cluster) gauge. Therefore, I expect that a faulty speedometer gauge would not interfer with the overdrive signal from the sensor to the PCM. I don't know which version of VSS the '87 transmission had originally because it was missing when I purchased the van.
THE QUESTION: Is my problem due to incompatible VSS adapter installed on the transmission; are VSS adapters interchangable across model years? Or can something else be causing the speedo/overdrive failure?
I have checked the condition of the wiring and connector, all seems ok. According to the wiring diagram, it would appear that the speedometer gauge can fail without affecting the VSS signal to the PCM. I mean, I don't think speedometer gauge failure would necessarily cause the overdrive failure. I am thinking about putting an older version (2-pin) VSS sensor on the transmission and splicing a 2-pin connector onto my harness to replace its original 3-pin connector. Is that unecessary?
THE ISSUE:
Speedometer will work intermittently (almost never works). When the speedometer is working the overdrive works normally, when the speedometer quits (while driving) the overdrive downshifts to 3d gear or won't engage (unless the speedometer is working).
The wiring diagram shows that the wire from the VSS which runs to the PCM splices-off to the speedometer (cluster) gauge. Therefore, I expect that a faulty speedometer gauge would not interfer with the overdrive signal from the sensor to the PCM. I don't know which version of VSS the '87 transmission had originally because it was missing when I purchased the van.
THE QUESTION: Is my problem due to incompatible VSS adapter installed on the transmission; are VSS adapters interchangable across model years? Or can something else be causing the speedo/overdrive failure?
I have checked the condition of the wiring and connector, all seems ok. According to the wiring diagram, it would appear that the speedometer gauge can fail without affecting the VSS signal to the PCM. I mean, I don't think speedometer gauge failure would necessarily cause the overdrive failure. I am thinking about putting an older version (2-pin) VSS sensor on the transmission and splicing a 2-pin connector onto my harness to replace its original 3-pin connector. Is that unecessary?
