Dashboard wiring loom help

PaulBucklandUK · Post by **PaulBucklandUK** » 01 Jun 2024, 10:19

Hi Volvo fans

After many years of a shabby interior I bought a full donor replacement and fitted it. The problem I have is the speedo and rev counter don’t work and an abs lamp is on.

There are no codes and using a diagnostic tool I can see the rpm and speed on live data.

I have found out that although they are both 1998 cars mine is a MY98 and the donor is an MY99.

The easy fix would be to swap the wiring harnesses over but I kind of ditched the original before checking it all worked.

Any help or advise much appreciated

Post by **scot850** » 01 Jun 2024, 16:20

Hi and welcome!

The dashboard wiring harness is different over here between 1998 MY and 1999MY. I am not sure if this is the case in the UK. Does your 98 have a cable throttle and the 99 an electronic one? The ABS module for a 98 and 99 I believe may also be different. Check the ABS module cover for the part number and compare with those listed on Mid-west ABS website to see if they are the same. They may have different part numbers but operate the same way as Volvo changed the numbers so often. It is more likely they are not the same.

Neil.

PaulBucklandUK · Post by **PaulBucklandUK** » 03 Jun 2024, 09:43

Hi Neil. Yes my car has manual cable. The donor had electronic throttle sensor.

Post by **scot850** » 03 Jun 2024, 13:03

I swapped my dash over due to the mounts being totally destroyed. The dash came from a 98 but the harness was different on this car.

So you may have to swap the dash wring harnesses over.

However, there may be another cause for your issue. The ABS module may be bad or as suggested the wrong one for your new dashboard wiring harness. I may be reading into this, but was the ABS all good originally before the swap?

The ABS not working correctly will affect the speedometer. Not sure if the rev counter is affected by the ABS module. That may be a harness issue to the speedometer cluster from a different wiring harness.

Neil.

PaulBucklandUK · Post by **PaulBucklandUK** » 03 Jun 2024, 13:52

The abs module was good recently repaired. The cluster is the original. The only wiring that has changed is the loom mounted to the dashboard. All other wires and modules are the originals. I tried the donor cluster and that had the same issue. I can only imagine some of the wires in the loom are different. I no longer have the original loom. As it seemed unlikely that a loom would be different.

Post by **scot850** » 03 Jun 2024, 19:22

Unfortunately for you, Volvo did a major electrical update in the 99 MY with many changes to things like the airbag triggering, heated seat wiring, dashboard wiring and more. Again there are different ABS modules even in the same years. The ABS module can have TRACS or STC options. STC was often the FWD car option and TRACS the AWD. But again the ABS modules changed in 98 to 98. You will need to get a mirror on a stick and look at the lid of the ABS module to find what you have fitted part number wise to your car. The dash may have an STC or TRACS button which allows them to be switched off. Some cars did not come with the button but you could fit the appropriate one by popping the blanking plate off and it was prewired behind.

So worth checking the ABS module you have currently on your car with the one of the donor and then check their part numbers on Mid-west ABS. If they are not compatible then the harness may be the reason. Sorry.

Neil.