Need some help or ideas.

EU- Spec, 1990 300ZX Twin Turbo Targa Manual 2+2

The ABS light appears when I start driving, but disappears after the car is shut down. Any possible reason for this?

I’ve already checked a few things: all ABS sensors have been cleaned and inspected, and the wiring shows no signs of wear or damage. The ABS control unit showed five long red lights, which should indicate code 50, but as far as I know, it’s not an official code.

The speedometer isn’t working, so that might be related to why the ABS light turns on after driving. We removed the Vehicle Speed Sensor (VSS) located near the transmission, and everything appeared fine—nothing out of place. The VSS should send data to the ECU, right? Before it goes to the speedometer.

Any help would be greatly appreciated.

Thanks!

Eric

The speedo gauge itself has a signal processing function from the speed sensor (analogue wave form) to the electronics for the ECU/HICAS/Power Steering/Cruise Control and the odometer. Was the odometer still working after the speedometer failed?

It is worth checking the speed sensor for this fault condition:

https://www.300zx-owners.club/forums/topic/161221-1993-tt-lwb-in-black/page/4/#findComment-1771548

The ABS Self - Diagnostics is below. ABS light comes on when there is a fault.

Hi AndrewG,

We tested the resistance of the driver’s side ABS speed sensor and found it completely unresponsive, there was no measurable resistance, suggesting the sensor has failed.

Since it wasn’t showing any signs of life, I’ve ordered a new replacement from the USA to fix the issue properly. Once it’s installed, we’ll be able to confirm whether this resolves the ABS fault and any related speed signal issues.

Thanks! I'll update when it arrives

Eric