1998 Tacoma 5vz-fe, Manual, 4x4

A few months ago my triple gauge (Speed/Tach/Odo) began dropping out as I was driving.
It would come back on when I restarted the truck, so I got in the habit of a rolling bump start in 5th gear to get the gauges back.... I know, probably not the best idea, but hey....
This went on for a while, then finally the gauges wouldn't come on with a start anymore and I got a P0500 Vehicle Speed Sensor fault.

I replaced: the VSS (level: easy). I only replaced the sensor, not the plastic gear inside as it looked to be in good shape.
After clearing the codes then pulling ECU breakers for a bit, it worked great... for a couple drives, then started again but not very often.

It took a couple of months but the gauges dropped out with increasing frequency, then there was a positive spike on the speed and tacho, then they dropped to zero & the odometer LCD went blank.
The positive spike was different than the previous failures where they would just drop to zero then come back with a restart.

So now I have the CEL again, and I bought a bluetooth obdi scanner. With Torque Pro installed on my phone, it shows tach reading with reasonable values, but the speed reading stays at zero.
This indicates ECU is not getting the VSS signal?

The way I understand the system is:

• the VSS produces a pulse with rotation that goes (back through the instrument cluster?) to the ECU,
• The ECU produces a linear signal that drives the needle in the triple gauge.

I'm worried there could be an ECU problem, since the tachometer goes through there too, or it could be a triple gauge problem...

Wiring/connector issues at the ECU or dash would not explain why it began working again after replacing the VSS.

I'm curious what tests you'd try next?
I've thought of these:

a) check vss output by tapping the wires and looking for the pulse signal
b) Take apart the dash and check connections there.
c) Find the ECU and check connections...
d) take it somewhere...


Thanks!

 

Had the same symptoms and I replaced speed sensor on tranny then Ecm check engine light still came on.Pulled out schematic and the only other thing left was the cluster. Problem fixed.

 

"the only thing left was the cluster"

So what did you do? Was the cluster the issue? Did you replace the cluster? Did you fix it? Replace a wire?

I'm having the exact same issues on my 3.4 swap. If I find anything, I'll post it up here.

I believe the issue lies somewhere in the cluster wiring. The tachometer signal is split: one wire to the ECM and one to the cluster. The speedometer wiring is slightly different: it goes directly to the cluster first, then passes the signal on to the ECM.