Xjs facelift 4L auto transmission warning light.

[Graham C]

For a few months, the auto trans warning light has come on intermittently. Usually, or always on a cold start.

I had a fluid and filter change done. However, on picking the car up, the garage said that the filter was not the metal box type filter, but a mesh one.

I can't find any info to mention a mesh filter. They cleaned it out. But the light can still come on.

Usually the light doesn't come on the third start and the car runs perfectly.

The car is a japanese import and many of the specialists I've contacted don't like the thought of that. But a gearbox is a gearbox.

Can anyone help please?

[LairdScooby]

A few things come to mind, first is what fluid did they use in the gearbox? Second, what condition is the battery in? If the battery is not holding its charge that well, it can cause spurious faults on the gearbox ECU and other ECUs as well. The clue here is that it happens after a cold start, when there has been the most load on the battery to start it. By the time you've started it for the third time in the day, the battery would (or at least should) have enough charge to cope with a warm start without dropping the voltage enough to cause a spurious fault.

As you might guess, my thoughts are directed at the battery being at fault here!

Recently on my S Type, i hadn't used it for about 3 weeks and when i started, it came up with "Auto Gearbox Fault". I ignored it for a few miles, then hit the clear button and it went off and stayed off - hasn't returned since so i'm assuming that it was just a low battery. Sometimes it will also try and tell me a tail or brake lamp (sometimes both on both sides!) have failed as well if i haven't used it for a couple of weeks.

[Graham C]

Hi Dave,

Many thanks for your thoughts.

I did put a new battery on but that did not cure the light. It may be a slightly less amperage than required, but the size of the tray was critical.

 

When I start the car from cold 3 times, it's one after the other.

The car is always on a trickle charger.

I now turn the ignition on and wait 5 seconds before starting. Touch wood, the light hasn't come on over quite a few starts. I don't know what made me think of doing this but I'm hopeful.

Cheers.

Graham.

[LairdScooby]

Just a weird thought here Graham, do you have an overdrive button for your gearbox? If so, try cycling that off/on a couple of times before turning the ignition on.

[Graham C]

Hi Dave.

There is a sport button increasing the revs before changing gear.

I'm not sure what that would do but appreciate the input.

As I said, waiting 5 seconds from ignition to start up is working for now, keeping fingers crossed.

Cheers.

Graham.

 

[LairdScooby]

I'm not familiar with Japanese imports Graham so i had wondered if they had use an Aisin-Warner transmission instead of the ZF usually fitted. Experience with an AW in a Volvo 760 taught me the overdrive switch could sometimes play up bringing up a warning light indicating overdrive was off.

From what you say, i'm guessing you have the more usual ZF box, some of the later 5-speed auto ZF boxes had their ECU mounted inside the gearbox, the seal could fail and this rendered the gearbox dead. This was more common on late 90s V8 models (X300 usually) but as you have a Sport mode, there is some electronic control. On the 4-speed if memory serves, the ECU is remote from the gearbox but i'm not sure where.

If you can locate the gearbox ECU, follow the wiring from it and there should be an earth point somewhere nearby, i'd remove the connector and clean the connector and earth point - everything you've said so far points to a bad connection of some sort, probably an earth.

[Graham C]

Hi Dave.

Wow, you know your stuff.

Thanks again for your input. I'll look into your suggestions.

Cheers,

Graham.