French driver, Spanish registered, British imported and US made Extreme Sport CRD geezer !

[Jeepbwoy]

Hi all !! pleasure to have made it here finally after owning a Liberty (Extreme Sport Cherokee) many years now. First acquired my Jeep 15 years ago in the UK and since relocated to Spain where we are both much happier. Just came across this forum as I ran into a strange issue following a turbo replacement recently. Everything running seemly well for a few miles but then the speedometer suddenly stopped working followed shortly by the ABS and brake indicator lights staying on. I suspect the VSS sensor, Earth or wiring from the vss sensor to be at fault but weirdly unrelated to the Turbo replacement. I guess its possible a wire got trapped somewhere but I will check resistance on the vss first I think. Any tips most welcome ! Being the optimistic type, at least I discovered this new group of pals thanks to this issue so not all lost after all Happy troubleshooting folks.
Additional info regarding fault, RPM working fine and automatic gears also as I have done 1000kms past couple weeks with live issue, very good fuel economy as I cannot accelerate ! Also did the reset test and speedo needle works fine.
I will check for resistance on vss sensor and it would be great to test for continuity between connector and PCM but which of connectors and which pins? pictures would be great ! Thank you

 

[KJowner]

I'd check the rear ABS sensor and it's wiring, the whole setup relies on the signal from that.

 

[Jeepbwoy]

Thanks for the reply! I had an hour this morning so I checked the vss sensor (before seing your message) and the sensor is open cct across its terminals so i assume it is dead right? Additionally, I hooked up the voltmetre on dc voltage and nothing read there either across the yellow and striped yellow wires so it seems like a double fault on the same cct. I assume they are both related, one leads to the other? anyway, I will get a new sensor and replace it once I get a reading across the wire terminals. The other end goes to the heavily heatsinked box under the bonnet being the battery right? If so, does it source the dc voltage to the sensor from there? Finally, if the two wires carry both dc and receive ac, an integrated capacitor sits inside the sensor casing right? Any fuses involved in series or does it go straight form the pcm to the sensor?

 

[KJowner]

As far as I know it's a Hall effective sensor so it won't have a supply

 

[Jeepbwoy]

As far as I know it's a Hall effective sensor so it won't have a supply

Hello, just a quick update to confirm that the VSS sensor above the rear differential was indeed Hall Effective and thus no power required. Whilst changing for the new one, I discovered the copper conductor inside the wire close to the terminal connector was open cct and so once fixed, all warning lights off and the speedometer worked again. I updated the sensor anyway as I had already bought it so I dont know if the old one had any problems in the end but problem solved so all good.