is the VSS sensor required for the A4LD to function properly??

[rhauf]

my 93 explorer won't shift into overdrive, i'm thinking it is because there is no VSS sensor on the new axles i put in. is this VSS sensor required to tell the computer when to engage overdrive?

note* i also replaced the transmission at the same time, the TCC works fine in 3'rd, there is just no 4'th gear. so i don't suspect it is the trans.

 

[Maniak]

The VSS isn't on the axle. The ecm gets the speed from that little adapter looking things near the end of the speedo cable by the trans/transfer case (driven gear side).

I can't say whether it needs it or not, but I know it will go into OD and 3/4 shift even if the speed is "bouncing" so I'm thinking if it uses it, it doesn't use it as a precise sensor.

~Mark
EDIT: Do a KOEO test.. if it shows the OD solenoid is an issue, double check the wires from the trans. They run very close to the exhaust manifold and if the factory "clip" comes loose they can fall into the manifold and melt.

 

[rhauf]

Okay, well the speedo works fine. so i guess that's not the issue then. i'll look elsewhere for the problem..


i know someone with a shop manual that covers my year, so i'll barrow that and get at the electrical troubleshooting (barf)

 

[Diff Whack Daddy]

Okay, well the speedo works fine. so i guess that's not the issue then. i'll look elsewhere for the problem..


i know someone with a shop manual that covers my year, so i'll barrow that and get at the electrical troubleshooting (barf)

The actual speedo on the dash is mechanical. There is a sensor on that mechanical cable on the back of the t-case that converts the mechanical rotation to an electrical signal that the ECM uses. You can also check the kick down cable. Look on the top of your gas pedal where the throttle cable connects and you'll see a second cable. That's your kickdown. The adjuster is on the opposite side of the firewall and may be too tight preventing it from shifting in to overdrive.