bf mkII fault U0121

[VX L67 Getrag]

Hi all,

I just picked up a cheap 10/06 falcon sedan with zf 6sp auto & has no other fault codes in engine or abs but in the trans controller it has U0121 (lost communication with abs) & it has no speedo because of this I’m assuming & put it in limp mode!

I’m wondering if anyone else has come across this & may have an idea of what to look at?

[VX L67 Getrag]

F9420DEF-1442-4F13-8128-137578DC4D73.png

According to a quick google it should be fairly simple, but wiring all looks normal...

[80gus]

I've had this before swapped speed in from abs to tcs, and disabled vid and it fixed it, was a FG tho.

[VX L67 Getrag]

Thanks for the info, I’ll try it out!

I’ve asked someone else who’s dealt with these more often but no response so I’ll keep everyone updated!

Thanks again

[VX L67 Getrag]

So a bit of an update...

When all faults are cleared & reset the speedo works until it gets to about 40kmh then warning light's flash on dash & speedo cuts out & then everytime it gets to around 40kmh the TCS & ABS & skid lights all flash on.

The other strange thing is although the speedo doesn't work it still clicks over trip metre/odometre but I don't think it's correct as it normally smack on 30kmh drive to work & think it only registered 20kmh.

So I tried swapping speedo source & disable VID but that stops the speedo from even working for that first bit, strange thing with the BF it's set by factory for TCS so I changed it to ABS... the other option there is OSS but I'm not sure what that is & can only assume maybe speed sensor on G/box but I don't think the ZF's have them.

[80gus]

OSS is a digital speed reference for B series only, via pin B7 on the ecu.

[80gus]

So a bit of an update...



So I tried swapping speedo source & disable VID but that stops the speedo from even working for that first bit, strange thing with the BF it's set by factory for TCS so I changed it to ABS... the other option there is OSS but I'm not sure what that is & can only assume maybe speed sensor on G/box but I don't think the ZF's have them.

PCMtec gives more options. but sounds like there is a genuine issue, try a ABS module reset with forscan or similar.

[VX L67 Getrag]

Yeah I think it’s a hardware issue & 99% sure it’s in the abs, I might change vas source back & leave vid disabled.

I don’t have forscan with activation but strange thing is I used my Gscan with latest updates to delete ALL faults & couldn’t remove abs communication issue, but forscan free version did straight away!

So many tools workshop’s need to do various models!

[VX L67 Getrag]

I'm starting to think "maybe" the disable VID in HPtuners helped & thats why FORScan could clear faults but the Gscan couldn't.. time will tell!

I enabled the FORScan for the free period & hopefully it will help with finding issues as I think it may be a module replaced with mismatch, but as I haven't used it before it will take a bit of playing with to figure out each section.

[VX L67 Getrag]

Has anyone got a BF MkII sedan with ZF 6speed that they can get a screenshot of the abs module info, I changed mine & didn't keep a backup of what it was before I changed it but it now say's invalid....