No tachometer and spedometer 1998 Volvo S70 Topic is solved

WinDVD · Post by **WinDVD** » 18 Feb 2026, 20:33

Hello all, I am having a strange issue with my cluster and possibly ABS module?
For reference, this is a manual base model car with traction control.

Most of the cluster works, (engine temp, fuel level, etc)
The only parts that seem to not work are the speedo and tach, and the ODO goes to "------" after SRS light goes out. ABS Light will remain on too. Speedo and odometer I do expect because the ABS module is suspect condition, But shouldn't the tachometer still work despite the condition of the module?

Even still I took a crack at the ABS module repair and managed to get rid of the wheel speed sensor codes that were there, but the ABS light is still on the dash despite no codes in the module (checked using 850 OBD-II app)

I tried the cluster test option in the "850 OBD II" app and one of the CAN INIT commands fails (but does not fail for any of the other CAN commands). It's quite the strange issue, Does anyone know if this is a cluster problem or an ABS problem? maybe both?

I also tried the motor test option in the ABS module section of the app and it did activate the brake pump motor, so the module is communicating at least. Is it possible the ABS module is causing both bad tach and speedo? Or is something else happening here?

It's also worth mentioning the car came in this condition, so i'm not sure when the cluster problems started happening or if it was an intermittent problem at first.

If anyone has any advice on what I should do here please let me know, I am rather stumped here. Thanks in advance

Post by **matthew1** » 18 Feb 2026, 22:08

Do you know anyone with a P80 to swap in a known good ABS module? Or in worst case, buy a used one from someone parting out a P80... if it's not the module, sell it and lose $10 or $20 in the process.

Post by **scot850** » 18 Feb 2026, 23:10

Try a simple test. Find something to wedge between the power cables and the body of the ABS unit. Putting a small wedge like a piece of cardboard or a golf tee (a buddy did that)between the cable and the ABS body pushes the contacts that usually fail first inside the ABS unit against their respective contacts. If the ABS and TRACS/STC (depending on car) go out and the speed and rev counter restore themselves, then the ABS unit is needing resoldered. This is NOT 100% successful and it is not a long term solution. It is just a simple test to try to identify an issue. If this restores function, contact our friend Matty at Mid-West ABS for a restored and warranted unit.

Good Luck,

Neil.

WinDVD · Post by **WinDVD** » 18 Feb 2026, 23:39

Hello, Thank you for the reply! I actually did buy a 2nd ABS module from a junk car, It was bad (someone hacked it apart, but the joints were untouched). I soldered that module too, since it had codes for the pump and speed sensors too.

But with it soldered (checked the points with a multimeter) it's still doing the same thing as the module that came with the car. (no ABS codes with scan, no dash speedo/tach + ABS light on dash)

Sadly I do not know anyone with a known good module to 100% rule it out, but it would be strange if 2 different modules have the same symptoms.

Is it known behavior for the tachometer to die with ABS module out? Or is it only supposed to affect the speedometer? Could it be bad solder joints in the cluster itself? Using the Torque Pro app i can get an RPM reading reliably there.

And also no amount of shimming the plug seems to fix it sadly, I'm kind of thinking it's something other than the module but honestly I'm not sure. It really is a strange issue.

Post by **abscate** » 19 Feb 2026, 04:25

It sounds like DDM/ I do have a spare but it’s way up at the North Pole. I will head up there soon.

WinDVD · Post by **WinDVD** » 19 Feb 2026, 04:31

abscate wrote: ↑19 Feb 2026, 04:25 It sounds like DDM/ I do have a spare but it’s way up at the North Pole. I will head up there soon.

Ah, I'm not sure what a DDM is since this is my first time working on a Volvo car lol, Where is this located in the car and how can I check it?

Post by **abscate** » 19 Feb 2026, 04:33

WinDVD wrote: ↑19 Feb 2026, 04:31
abscate wrote: ↑19 Feb 2026, 04:25 It sounds like DDM/ I do have a spare but it’s way up at the North Pole. I will head up there soon.
Ah, I'm not sure what a DDM is since this is my first time working on a Volvo car lol, Where is this located in the car and how can I check it?

Sorry, driver display module. It’s the dash unit you look at from driver seat and has a lot of stuff in I

WinDVD · Post by **WinDVD** » 19 Feb 2026, 04:35

abscate wrote: ↑19 Feb 2026, 04:33
WinDVD wrote: ↑19 Feb 2026, 04:31
abscate wrote: ↑19 Feb 2026, 04:25 It sounds like DDM/ I do have a spare but it’s way up at the North Pole. I will head up there soon.
Ah, I'm not sure what a DDM is since this is my first time working on a Volvo car lol, Where is this located in the car and how can I check it?
Sorry, driver display module. It’s the dash unit you look at from driver seat and has a lot of stuff in I

Ah I see lol, If that's the case, is there a way to verify this is the fault? Or should I just take it apart and inspect the board for damage that way? I've been meaning to replace some bulbs in there anyway.

WinDVD · Post by **WinDVD** » 19 Feb 2026, 06:45

UPDATE: took the car out on a test ride, ABS and Traction Control are working properly, I heard and felt the ABS pump enable when I did a test brake. Despite the dash saying otherwise. I suppose that rules out those (hopefully anyway lol)

Tach and speedo are still dead though, and the ABS light remains on

Post by **scot850** » 19 Feb 2026, 08:29

There is a speed sensor on the transmission. I can't recall how it works on the 1998 and older model. DDM as Abscate mentions could be an issue.

Do you know if the dash top has been removed at all? I had issues with my 00 V70 at one point and eventually discovered at some point someone had it apart and not refitted the connector on the back of the unit correctly so it was loose.

Neil.