D2a TD5 - no speed signal

[twr7cx]

Recently my D2a TD5 HSE has developed an issue where no speed signal seems to be received. The result of this is an amber ACE warning light on the dash (it's on my to do list to connect the Nanocom and read the code), speedometer doesn't function (just reads 0km/h), cruise control doesn't work (I tried out of interest) and the doors do not automatically lock (they usually do when traveling above 7km/h).

Usually while driving the speed signal will suddenly come through, the doors will lock instantly and vehicle will then drive as normal. Initially this would occur after a few seconds of driving, more recently that time has gotten longer and it can now be after a few minutes of driving or up to 10 minutes later in the journey.

Of note is that it has never stopped working when it's working.

Any thoughts or ideas?

[Outback 1]

Scott doesn't the speed signal come through slabs , i think a code read will be the best place to start other than that it's just guesswork

Sent from my SM-G900I using AULRO mobile app

[twr7cx]

I didn't realise that the speed signal went through the SLABS. I assumed rather the signal broke off and went to a variety of different places. So that's a handy start point, cheers.

[sierrafery]

IMO the most suspect is the road speed signal output from the SLABS, it's not easy to diagnose cos it's PWM signal switching between 0 and 12 volts at a frequency of 8000 pulses per mile so an oscilloscope is needed to check if it exists... the problem can be ''splited'' in 4 variants:
1. no VSS output from the SLABS => you need to replace it(let's hope not but quite unlikely cos then you should have seen the 3 amigos too), maybe a dry joint on that output
2. a bad contact/corrosion at the SLABS plug - output = C0504 pin 3(pink/green wire)
3. bad contact in header C0290 where it splits between all systems the wire comes directly from SLABS into pin 19 then it splits and goes to each system with same colour wire to all(let's hope not cos this header is embeded in a harness not very easy to reach)
4. interrupted wire between SLABS and C0290
see RAVE - Electrical library - connector views

code reading might not help you much just confirm the symptom, i presume you'll get "road speed missing" or similar fault code from ACE and engine ECU and no current code from the SLABS(maybe only some hystorical) cos if it was a bad contact in the wheels speed sensors input connector C0505 you deffinitely should have got 3 amigios and fault codes for all sensors.

[twr7cx]

I've got a Truespeed fitted somewhere along the way to correct the speedometer for the larger tyres fitted. I wonder if that is perhaps causing a fault, but I had assumed that this would be after the SLABS in the system and only effected the speedometer...

[strangy]

I've got a Truespeed fitted somewhere along the way to correct the speedometer for the larger tyres fitted. I wonder if that is perhaps causing a fault, but I had assumed that this would be after the SLABS in the system and only effected the speedometer...
Exactly the answer to the question I was about to ask.
Id check the connections there first.
Maybe disconnect it if no poor connections found. This should at least give you a reading even though incorrect and rule out the SLABS.
Does the truespeed come with a bench test procedure?

[sierrafery]

I presume the truespeed is connected on the SLABS output between C0504-3 and C0290-19(third wire from the bottom, this pin can be other number in reality but the wire colour is the same) after that the VSS(vehicle speed signal) splits to all systems and if it's there it can be very suspect that there's a bad contact or something, i attach you the relevant part of the diagram, follow the pink/green path starting from C0504-3(this is the VSS) and you'll understand what i mean even if you are not electronist

[strangy]

TD5 Speedo correction - no not the boardies! :) (http://www.d2au.com/index.php/topic,201.msg859.html?PHPSESSID=3a965f102c7f906dd3 f19065439d68b5#msg859)

This link may help if you didnt install the truspeed yourself.
After reading this Id probably check you power connection to the truspeed first then go from there.

[twr7cx]

Cheers. Pretty sure that is the guide I followed when I installed it years ago. Will have a look over the weekend.

[twr7cx]

Bypassed the TruSpeed at the ECU plug connection and no issues occur. Used the full wiring for the TruSpeed, but still bypassing the unit and still no issues which indicates the wiring is fine.
Tested the positive power and earth wiring for the TruSpeed and no issues. Shakes and wiggled the wiring and connections and no loss.
I can therefore only assume that the TruSpeed unit is faulty and failing. Opened it up:

https://www.aulro.com/afvb/images/imported/2016/07/790.jpg (http://s1185.photobucket.com/user/twr7cx/media/IMG_7040_zpsaaveprne.jpg.html)

Looks like they've covered all the electrics in some black gunk making it unrepairable.

I feel as though my only option then is to replace with a C6100-4 unit.

[Slunnie]

Also check the Truspeed is getting power and give the potentiometers a little tweak to make sure they haven' burnt in a localised position. Likewise try the alternate speed setting incase a part of the circuit has failed that can be made redundant.

[twr7cx]

Also check the Truspeed is getting power and give the potentiometers a little tweak to make sure they haven' burnt in a localised position. Likewise try the alternate speed setting incase a part of the circuit has failed that can be made redundant.

That's a good idea. I only run one set of tyres so have never used the toggle switch. I might test the other setting out.

While driving this afternoon with it all reconnected, it wasn't working. I gave the unit a tap and it worked again. I wondered if something is loose inside it but there's nothing visibly loose or rattling.

[Slunnie]

That's a good idea. I only run one set of tyres so have never used the toggle switch. I might test the other setting out.

While driving this afternoon with it all reconnected, it wasn't working. I gave the unit a tap and it worked again. I wondered if something is loose inside it but there's nothing visibly loose or rattling.
Ahhh, I bet that's somewhere in the wiring that's not glued down and has fatigued or a dry joint.

[CU55TM Disco]

Is it worth the risk to try and remove some of the potting (black gunk) around where the wires go into the circuit board, maybe there's a dicky joint there. Sharp Stanley blade and a bit of patience... And a few brews...

[rob tilbury]

Hi the black gunk is low temp tar or a silicone mix ,,,( for water proofing )
If its lo temp tar (you can smell it )
A hair dryer will let it drip out on heat setting ,,, you will find its most likely the transistor on the top left could also be one of the multy turn VR ( the blue plastic resistors )

If you like i can test the TR and VR`s for you ,,,, ?

[twr7cx]

So, did some testing. With the top off, if I push down on the yellow wire, the speedo works again.
I cut open the back. Got lucky that the black stuff either hadn't been applied properly or didn't stick well in this area.
The joints looked a bit dry, redid two of them, sadly not the fix. Removed the yellow wire and made up a new one - still didn't solve it. I think there must be something wrong further along, perhaps a crack in the board or something.

I've given up now and ordered a C1600 Ratio Interface Unit from Hunter Di Spare Parts Company.

[twr7cx]

Hi the black gunk is low temp tar or a silicone mix ,,,( for water proofing )
If its lo temp tar (you can smell it )
A hair dryer will let it drip out on heat setting

Sorry, forgot to mention that I tried this with a heat gun. Even on full heat it wasn't melting at all. It's hard like plastic when cold and still hard like plastic when hot (it was far too hot to touch for more than a split second) after being heated.

[Farva]

I'm having the same problem, haven't opened the truespeed yet will see how I go, might try the toggle switch too, could be another for a c1600-4

[twr7cx]

Interestingly enough, two years later, with a fully functional C1600 Ratio Interface Unit from Hunter Di Spare Parts Company I'm getting the error again - "(22,1) ROAD SPEED MISSING, (LOGGED)."

Doesn't seem to be having a negative effect on the vehicles operation though.

[biggin]

Interesting. I’m having a similar problem but don’t have a speed correction device installed. In the last couple of days, for the first start of the day, the speedo doesn’t work and the odometer doesn’t count. But only for about 10 minutes and then comes good. No warning lights present throughout. Very strange.

[twr7cx]

Interesting. I’m having a similar problem but don’t have a speed correction device installed. In the last couple of days, for the first start of the day, the speedo doesn’t work and the odometer doesn’t count. But only for about 10 minutes and then comes good. No warning lights present throughout. Very strange.

My speedometer and odometer are working fine still even with the error.

[Werdenfelser]

Interestingly enough, two years later, with a fully functional C1600 Ratio Interface Unit from Hunter Di Spare Parts Company I'm getting the error again - "(22,1) ROAD SPEED MISSING, (LOGGED)."

Doesn't seem to be having a negative effect on the vehicles operation though.


I have this fault, no effects on Speedo, no Amigos, no effects on ABS, HDC or CC.
But: Amber ACE Light.
Stored Fault „Road Speed Signal Missing“ at ACE.

D2 TD5 Automatik with 265/75 and obviously working Hunter Di unit.

Where should I start to look for a fault? What do you think?

[d2dave]

Every time I plug Nanocom in I get the "road speed missing" fault. I have been getting it for years.

Every thing works as it should. I too have a speedo correction device, for around 10 years.

I have just assumed that this was the cause of this fault.

[Werdenfelser]

So you don’t think the ACE Light doesn’t belongs to the Speed Signal Fault?

[onebob]

I have this fault, no effects on Speedo, no Amigos, no effects on ABS, HDC or CC.
But: Amber ACE Light.
Stored Fault „Road Speed Signal Missing“ at ACE.

D2 TD5 Automatik with 265/75 and obviously working Hunter Di unit.

Where should I start to look for a fault? What do you think?

Check your rear axle ABS cable plug and socket connectors are clean and dry, and that the cables are all secured and not ‘flopping’ about. I wrapped some electrical tape around my left rear connector because the plug was a little loose in the socket. It has been all good now for a couple of years. Also the Hunter DI installation instructions are a little cryptic when it comes to working out which wires to use. Which colour wires on the Hunter unit have you used for signal in and signal out?

[shack]

For anyone suffering these faults "road speed signal missing" etc etc, and with the Hunter Di fitted, I'd take a punt that it has been fitted at the actual slabs ECU output.

I have no issue with this unit, but I'd suggest to avoid these faults, and to fix poor gear shifting on the auto (if you have one), that you fit the unit just before the Speedo, no guarantee it'll fix these problems of course, but for some of you it will.

Cheers
James

[Werdenfelser]

Check your rear axle ABS cable plug and socket connectors are clean and dry, and that the cables are all secured and not ‘flopping’ about. I wrapped some electrical tape around my left rear connector because the plug was a little loose in the socket. It has been all good now for a couple of years. Also the Hunter DI installation instructions are a little cryptic when it comes to working out which wires to use. Which colour wires on the Hunter unit have you used for signal in and signal out?

Thank you!
Checked everything and everything fine.

The Hunter Box is running since 5(?) Years. No problems so far.
But had a lot of problems with ACE. All mechanical. Changed all pipes, new pump and so on. Was fine for a year or so.

The last month amber light.

Checked all electric connections and sensors as far as possible for me.
Put a new ACE ECU in.
Nothing. Still amber light.

Drove to the city a week ago. Starting there, Red ACE light…

Aaargh…

Ordered non-ACE ARB‘s and all the stuff.

And imagine what?

No lights since…



And I can confirm: „missing road speed signal“ makes no ACE Lights…