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Discussion Starter #1
Hi. I've owned my H6 Outback for the past couple of months now. It's a bit of a sorry tale so far!

In week 2 a series of fault lights showed up one day - Flashing sport light, and ABS / Stability Control lights on permanently.
When the lights came on this was accompanied gear change 1 to 2 being very long and slow, 2 to 3 coming in with a bang.

Stopped the car. Turned off the engine, restarted and the fault cleared and the gearbox shifted normally again, no fault lights either.

A couple of days later the same thing happened again. Only this time, everytime I cleared the lights and the fault by turning the engine off and back on again it would reappear a few metres down the road again.

On the third attempt the fault cleared and didn't return for until a half an hour later.

Diagnostics have shown a couple of problems pointing to the rear speed sensor and the TCU....Both relatively expensive just to try and see if it stops the problem, especially if it turns out to be something else!

Had the fluid changed last week. Two things I've noticed:

1. The fault doesn't occur quite as regularly as it used to (however once it happens the first time, it can either be cleared and not come back for miles, or it can keep reoccurring 3 or 4 times, cleared each time by restarting the engine, before it then disappears and doesn't appear again for miles)..

2. The gearchange when the fault HAS NOT occurred is much smoother than before.

When the fluid was changed there were some metal particles in the gearbox sump.

My questions are:

1. Does anyone know of any economical fix for this or a way of diagnosing the problem beyond doubt?

2. The garage in their haste weren't able to find the AT filter location so it wasn't changed (Before you say it.....I know!!!).
I was just thinking; If I have the fluid changed again, have the power-flushed to get rid of as much of the metal particles as possible, have the filter changed, refill with Lucas No-Slip and top of with proper Subaru ATF, do you think that will make things better?

Having the box refurbished is almost as much as the car is worth!

The plan is then to partially retire this Outback and use it for hunting and rural-work and get another one to replace it....This time with a proper warranty!!!

Thanks in advance for any suggestion.
 

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Sounds like the transmission switched to a "limp-home" mode and should be OK mechanically. Do you know exactly which fault conditions have been found?
 

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I am in love with romraider and freeSSM. Download them both, get the cable and a lap top and you're in for some real DIY diagnostics - these are tools you can use to beat the average guy at the dealer. Takes the guess work out of the equation.

You can log and trend everything that goes on both in your engine and transmission, read and reset all codes and reset both controllers if they have learned any bad habbits :).

Kind regards,

Tapani
 

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Diagnostics have shown a couple of problems pointing to the rear speed sensor and the TCU....Both relatively expensive just to try and see if it stops the problem, especially if it turns out to be something else!
How were the speed sensor and TCU problems diagnosed? Guesses, or were transmission On Board Diagnostics trouble codes found and if so, exactly what were they? If they were codes related to the speed sensor, what further investigation was done to try to confirm the fault?

On North American H6-equipped cars the AT filter is located in the left front fender area. If replaced, best to use the genuine Subaru AT filter -- it's built quite differently.

It might not be unusual to find some very small bits of metal in the pan, especially if this is the first time the ATF was drained out. However, if they were larger than, say, small shavings, and more than just a few, or if they were distinct chunks, then that might indicate a problem.

Don't use a "power flush" machine -- just do a drain and refill a few times.

I don't think we can say definitively whether or not changing the ATF and filter will resolve the problem, nor can we provide a way to diagnose beyond doubt, at least, not without further testing and, yes, sometimes substitution.

That's a 2004 H6. I believe that might have the 5-speed AT; is that correct?
 

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Discussion Starter #6
Hi and thank you to everyone who's replied so far. Apologies for not replying more quickly. I've been a little pre-occupied with non-car things.

OK, I had conflicting messages from two different Subaru main dealers. The first said they couldn't find any existing fault.
I had explained to them that turning the car off and back on again and then would reset the fault and turn the warning lights off.

They also said they'd checked the ATF level in the auto box and that was fine too.

The only fault they found was a historical one which they said pointed to a rear ABS sensor. Personally I think the Service Manager was guessing or had misunderstood what the technician had told him.

They did take it on a road test but claim they couldn't get the fault to replicate itself.
I left and 100 metres after driving out of the dealership, the fault came up again. Typical!

Anyway, a couple of days later the fault was coming up so often that I decided to take it into a different local Subaru dealer.

I left the engine running so that the fault didn't clear down and the technician told me that the following code had come up:

P1706 AT Vehicle Speed Sensor

After another 45 minutes further investigation the following had appeared:

C0045 TCM Malfunction (Current). Detail Code: 9720

The technician said it would require further diagnosis as he wasn't sure whether it was a faulty speed sensor causing the TCM to think it's faulty or whether it was a fault with the TCM that was causing the Speed Sensor to report a fault.
He was also pretty sure he wouldn't be able to find out!

It is a 5EAT box on my car.
 

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Not much of help, but C0045 is a generic OBD code for rear left wheel speed sensor... originally you had the ABS and VDC lights on too? Did the tech look into the ABS controller?

Tapani
 

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C0045 . . . .

That code is for/related to the ABS/stability system. I believe it is indicating that the ABS system self-diagnostics has identified some sort of malfunction in the AT control module. The two systems share a lot of information, such as wheel speed, gear position, etc., and if the ABS unit doesn't receive the required info from the TCM, it can trigger this code. The code itself isn't identifying a particular fault, only that things don't seem right over in the TCM. And because the ABS system isn't getting the info it needs, and can't function properly, it is shut down, thus the ABS and stability control warning lights, in addition to the flashing sport light.

When a C0045 code is triggered, the first step is to see if there are any transmission-related codes, and if there are, to deal with those. The P1706, therefore, remains the prime suspect, at least the way I see it.

There was 45 minutes of investigation before the C0045 appeared. I wonder what tests were done and what, if anything, was found. . . .

Do you have a maintenance/repair history for the car? Is there a possibility that any of the related control modules (transmission, ABS, or vehicle stabilty) had been worked on or replaced?
 

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Discussion Starter #9
It's certainly a possibility. The car has full Subaru service history from new.
When the independent garage I use took the sump off the bottom of the gearbox to change the fluid, we found some sort of adhesive/sealant. It had to be ground off!
Someone had certainly been in there before - Perhaps to seal an existing leak?

Here's a funny thing: I called my local dealer's parts department today to get a quote for a new speed sensor and harness (part number 24030AA120 now replaced by pn 24030AA121 ) - £450 GBP ($720 USD)....and two weeks back order from Japan.

Checked Subarupartsonline.com and theirs are $330USD which is about £200 GBP!!!!

However, I have also today come across a used gearbox including torque convertor from a 2005 H6 3.0 for £450.

So now I have a dilemma - Do I take the risk and presume it is the speed sensor and buy the Speed Sensor from Subarupartsonline.com and have it shipped over? A potentially expensive mistake if it's the TCM that's faulty.

Or do I spend the extra £250 on the complete box so that I can cannibalise it for the speed sensor?
That will leave me with the rest of the gearbox to transplant into the car if it's something else that's wrong, assuming there's nothing wrong with the replacement box!

Of course there is the third way - Change the fluid again, and flush out all of the foreign bodies in the transmission, but this time change the filter as well and see if that remedies the problem - But that's a £120 option in itself. The AT fluid is not cheap!

After your words above regarding the P1706/C0045 TC's I'm no longer all that convinced that flushing through and a new filter is very likely to fix it.

Either way I'm into a relatively large amount of money for an older car.

What do you think is the best way forward? I think I already know the answer, but I can hear my credit card complaining from my pocket!:)

Also - Do you know where precisely the Speed Sensor and harness are located? Are they actually inside the box or mounted outside? Also where is the TCM located? Is that inside the box?
Any ideas where I might be able to get a guide to how to replace the speed sensor, or a proper workshop manual with that job included?

Thanks again
 

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Subaru of America has a website where you can pay a $35 US subscription and download service manual files (pdf). The full manual is divided into many files (700 - 1000) and because downloads are limited to 50/hour, it might take some time; However, for a start, I would imagine you would be needing only the files related to the 5EAT transmission (repair, and diagnostics), so that would make it much more manageable. See:Subaru Technical Information System - Welcome and drill down under Online Reference. Of course, this would be for the North American version, but I would imagine it would be much the same if not identical. (I believe the 5EAT was introduced here in model year 2005, but possibly earlier elsewhere, so it might not show under 2004.)

There was a thread here with links to web-sites that have some manuals for download, and a Google search might find others.

If the adhesive/sealant was on the mating surfaces of the sump and transmission, it might be normal. Subaru doesn't use a distinct rubber or cork gasket there -- instead it's an RTV compound.
 

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Discussion Starter #11
Thanks for that. I googled around a bit after my last post and found a Subaru workshop manuals online.

It looks like, unless I am very much mistaken, that the Speed Sensor and harness is on the outside of the gearbox.

The workshop gives detail of how to diagnose the problem and solutions, but doesn't actually show you how to change the speed sensor and harness.

Still looking for a guide on that one please!

The bond/sealant between the bottom of the gearbox and the sump was pink if memory serves correctly.
 

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The workshop gives detail of how to diagnose the problem and solutions, but doesn't actually show you how to change the speed sensor and harness.
Is it a pdf? If you haven't already done so, try searching the file(s) for "rear vehicle speed sensor" or combinations of those words. (That's what it's called in the manuals).
 
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