406 automatic AL4 gearbox problem

[carlo14]

Hello all, should have joined this forum ages ago being a Peugeot nut and having had loads of them.

Would be very grateful if anyone could help with a weighty problem. Just bought a 1998 406 automatic and noticed very early on that occasionally the sport and winter lights flashed simultaneously. Unfortunately not konwing anything about this particular box I didn't know how serious it might be.

A transmission specialist has scanned it and said the gearbox oil is black/knackered (although has no 'bits' in it), and it has fault codes 48 (Park Neutral switch), 68 (Pressure Control) and 28 (Output speed signal).

Specialist A reckons it will definately need a new valve body at £795 but should be OK after that, specialist B said he wouldn't spend a penny on it as the box is probably shot. Strange thing is it drives beautifully and has only done 60,000.

I'm tempted just to change the oil and see if this will stop it flashing, anyone here offer me any advice? Having just spent £800 on a car I can't face the fact it may be useless!

Cheers

[CitroJim]

Hi Carlo14 and welcome to the forum

Specialist A is clearly not one and Specialist B may be nearer the mark but may not be. There are things to check and do first.

Oil in the AL4 will look horrible after a while and as long as it has no bits in it and does not smell burned, the 'box will live for a while longer.

The fault codes suggest your gear position switch needs a clean-up, the code 68 that the oil pressure is a little low and the third may be a red herring. How did he read these codes as I suspect they were not read using the pukka Pug DIAG2000/ Cit Lexia diagnostic kit which will tell you far more in text and not by fault numbers.

Change the oil soonest but note there is a special procedure to do this and not all of it can be drained as the torque convertor holds a large quantity that cannot be drained.

The guide on how to do this is in a post in the Citroen forum but here it is again:

AL4 Oil Change Guide

Note very carefully that this operation must be carried out at 60 degrees C and even more importanly, you must only use ESSO LT71141 oil. NEVER use ordinary Dexron ATF as this WILL kill the 'box! Esso LT is golden in colour and looks like ordinary engine oil.

Esso LT71141 looks like liquid gold and costs roughly the same. It is expensive and best bought in a 20L drum, especially if you do a succession of partial changes.

As it's impossible to fully drain the 'box. I'd carry out at least three partial changes in reasonably quick succession.

It's not a bad idea to replace the oil filter but that's a gearbox off and strip apart job. Not trivial at all.

After the oil is changed, you must then have the oil wear indicator reset and this can only be done using a DIAG2000 or a Lexia. If the oil wear indicator trips, the sport and snow lights will flash and the gearbox will enter "limp Home" or "emergency 3rd" mode where the only gears available is third and reverse.

The AL4 is verty similar to the ZF 4HP20 and much the same applies. there is plenty written in this forum on the 4HP20, including how to strip one!

If you want to delve further into the wonderful world of autoboxes, I have a load of valuable information on the AL4.

[carlo14]

Thanks Jim. I'll no doubt return to reap the benefits of your knowledge!

[reblack68]

Told you you'd get good advice here

[carlo14]

Indeed! My two 405 automatics just seemed to go on forever - different world these modern boxes eh? I sold new Peugeots for 12 years during this period but never really got involved with the mechanical side. The 406 did and does drive fantastically though.

[wheeler]

Specialist A is clearly not one .

That made me chuckle

[CitroJim]

Carlo,

One other thing i meant to mention is that if you have a proper DIAG2000/Lexia diagnosis carried out, it will tell you if any faults are permanant or intermittent. I reckon you'll find yours are intermittent and hopefully will clear and not return..

You may find this post interesting and useful. I meant to post it last night but the old brain was feeling a bit addled after a long day at work...

[carlo14]

Cheers Jim

One thing I have noticed on mine is that when the sport and winter lights are flashing I still have use of all 4 gears, whereas I thought that also meant reduced functionality, i.e. 3rd gear only.

Also looking at this thread am I wrong to assume that this flashing can mainly indicate the oil just needs replacing, or am I misunderstanding something?

http://www.savewalcotlibrary.co.uk/foru ... &view=next

Am getting the oil changed next week anyway.

[CXN406]

Good Afternoon.

Pleased to have found this post 16 years after original posting!

Sorry to bump an old thread for anyone who doesn't appreciate that-

I wondered if any members can point me to the AL4 oil change instructions that were linked to in the earlier posts as the links now appear to be dead (admitedly unsurprising after this long!).

I am custodian of 1998 registered 406 which is showing all the same symptoms with flashing lights etc.

From a cold start, moving lever from 'P' to 'D' position will generally give you normal driving without problems until the first time it is necessary to engage reverse for a three point turn etc...

As soon as the lever has been moved through R position and throttle is pressed, we get flashing lights and "safe mode". Dragging in low gears and will not change into top.

It seems to be possible to clear or avoid safe mode and resume driving normally if you turn the engine off then restart the car with the lever in the 'N' position and go straight to drive... My pragmatic brain says to me that it would appear to be something to do with passing the lever through the "R" position...??

I work in a garage (In an admin role, I'm NOT a qualified mechanic and don't claim to be!) which uses the Bosch KTS diagnostic system and wondered if I could learn anything useful from using that??

I have much the same situation as the original person that posted- The car is low mileage (60k) and basically bulletproof it just has this gearbox issue which isn't actually stopping it, but it would make using the car easier if we could solve it.

Glad to hear from anyone who can give useful advice.

Thanks

Luke

[lcwin]

Don't worry the auto is probably fine. AL4 is a simple autobox. Change the oil every 40k with esso Total or Renault new Syn for 4 speed and its fine. In fact contrary to general believes over filling by 500cc is fine just don't underfilled. Best is just follow procedure.
Change the gear speed selector . Its cheap and tend to fail bcos of extremely thin contacts inside . In fact a slight misaligned setting will give a fault code .Next change the pressure regulating valve and you r good. If you want but usually not needed is the clutch pressure valve .
If you drive a 2 litres n carry heavy loads Torque converter will ususally fail around 200k.

[CXN406]

Thank you Icwin.

Have managed to get oil change instructions and some Peugeot technical bulletins from a contact which should give most information.

Is is possible to get a replacement selector any more?

[lcwin]

It should be the same across all AL4 . I used to have citroen C5 2.0 with AL4, 206 with AL4 and now 2008 1.6 with AL4 all using same selector and oil. 2008 I switch to Total oil bcos its fully synthetic and runs better and hv much better shear life n viscosity vs temp stability. Esso version I think there r alot of fake oils which actually is generic ATF 3 .
Solenoid also exactly the same just make sure its original and not refurbished.

[lcwin]

ok if you change solenoid its best to check if its the normal black connector solenoid which is the standard for a very long time but yours maybe the older version. But from what I know most of the older AL4 also hv converted to this newer version but its better to check. If its still the older version you need factory reset

[ozvtr]

Is is possible to get a replacement selector any more?

I think he is talking about the selector position switch. They are easy to find on Ebay and Aliexpress. BUT unless you are having problems with the gear indicator on the dash flashing, I wouldn't worry about that. I am not talking about the "snow flake" flashing, I'm talking about the gear indicator flashing.
Change the oil first, then go from there.

[lcwin]

The best idea is do a scan. Low guide pressure is Pressure solenoid fault. Press on gas pedal the pressure should be within 10% or above guided pressure. If its pressure solenoid fault u will get occasional fault n run into safe mode 3rd gear.
The gearshift selector is very sensitive to positioning and internal damage track which is about 1mm width copper. Any intermittence contact will also give error.
Just do an oil change after the solenoid change and if its very dark do 2 rounds. When changing solenoid there is a magnet on the valve cover. If there is a lot of iron fillings there then u better start looking for a replacement