Blinking light between Drive and 4th gear on a 986 Tiptronic

[ClaudeJS]

Dear Ik,
Same phenomena happened to me last week: I left the battery disconnected for almost 2 months, until last week, reconnected, start the car => everything OK.
After a few miles I discovered that blinking light between 4th ear and Drive.
The car is running fine, no problem with the auto gearbox, except the manual mode is not working. I cannot shift gears from the steering wheel.

Any idea?
I read in the forum, maybe the multi-function switch is the culprit?

Help welcome!
JC

[Lil bastard]

The lights flashing as you describe indicate a fault in the tranny. The coolant shut-off valve is operated electrically, so your fault may be as simple as a blown fuse - check the fuse panel for the appropriate fuse. It could also of course be a faulty shut-off valve. This can be checked by jumping the pins appropriately in the trunk control box - this procedure must be done in order to flush the cooling system. If the valve opens when jumped, it's working properly.

Another somewhat common cause of this fault is a dirty switch at the tranny. This gets exposed to mud, water, dirt and can become inoperable - usually accompanied by an inability to operate the tranny in manual mode. You can pull the switch and clean it up, fairly simple DIY.

Cheers!

[ikkaro]

Originally Posted by Lil bastard

The lights flashing as you describe indicate a fault in the tranny. The coolant shut-off valve is operated electrically, so your fault may be as simple as a blown fuse - check the fuse panel for the appropriate fuse. It could also of course be a faulty shut-off valve. This can be checked by jumping the pins appropriately in the trunk control box - this procedure must be done in order to flush the cooling system. If the valve opens when jumped, it's working properly.

Another somewhat common cause of this fault is a dirty switch at the tranny. This gets exposed to mud, water, dirt and can become inoperable - usually accompanied by an inability to operate the tranny in manual mode. You can pull the switch and clean it up, fairly simple DIY.

Cheers!

Thank you so much for the advise. I am going to the blown fuse first, as the car just had the cooling system flushed (so I assume the shut-off valve should be ok). Will post back with results.

Cheers,

Raul

[ClaudeJS]

Maybe useful for all:
With an OBD code reader, I found the code P0740 "Torque Converter Clutch Circuit/Open"
I erased the fault and problem is gone, solved : no more light blinking, everything works perfectly!

So simple as that!

Lesson learnt: OBD code reader is mandaotry!

Thanks to all for the support,

JC

[Dale_K]

Simply erasing the code may not have corrected the underlying problem. My car is in the shop right now and one of the items is the 0740 code. I am hopeful that a Tiptronic service with fluid and filter replacement will have a positive effect on my car but I really won't know until I drive the car for a while. I hope your car doesn't need any additional work but simply clearing the code might not be enough. My mechanic thinks the Tip fluid gets contaminated with diff fluid and then the torque converter clutch slips. Personally I doubt it. I told him to go ahead and take a fluid sample for lab analysis but I don't know if they can really detect cross contamination or not.

I'm supposed to get my car back early this week and I'll post an update. It would be good news if the Tip service decisively fixed it because that's fairly easy and cheap. Stay tuned, as George Bush the elder used to say.

[bcorcoran]

Hi, I've just joined this forum - grate source of info.

My 2001 Boxster S tiptronic has similar symptoms: some gearbox slip & alternating fault lamp indications.

I'll have to look up the fault code provided from my dealer but their suggested fix was a gearbox overhaul as they claimed the torque converter was worn and residue evident in pan. I took the car to a transmission specialist who had trouble identifying any problems but we agreed to an oil & filter change and some further fault diagnosis. The specialist indicated no one had removed the pan previously and no evidence of residue from torque converter.

The filter & oil change improved the situation for low speed driving but at higher speeds I still get fault lamps, but not always and no slip, no noises, no fluid loss, in fact no change in performance ie can manual shift as normal.

From this forum & others it seems possible causes include wheel speed sensors, transmission plug/sensor or transmission control unit on boot (trunk) wall.

I hope others out there can sort this one!

[Malty123]

Originally Posted by Lil bastard

The lights flashing as you describe indicate a fault in the tranny. The coolant shut-off valve is operated electrically, so your fault may be as simple as a blown fuse - check the fuse panel for the appropriate fuse. It could also of course be a faulty shut-off valve. This can be checked by jumping the pins appropriately in the trunk control box - this procedure must be done in order to flush the cooling system. If the valve opens when jumped, it's working properly.

Another somewhat common cause of this fault is a dirty switch at the tranny. This gets exposed to mud, water, dirt and can become inoperable - usually accompanied by an inability to operate the tranny in manual mode. You can pull the switch and clean it up, fairly simple DIY.

Cheers!

Ive got the same flashing D and 4 lights, Where is this tranny switch located to check it?

And which pins need shorting to operate the coolant valve to check that?

Thanks

[tonythetiger]

I will revive this thread rather then start a new one.
2002 tip, 986 S with 80K

Flashing 4th and D after warm up, however transmission works fine and the normal lights come back in a minute or so, go to 4th and D again, etc as I drive. Automatic and manual function fine, just dont get the feedback in the dash lights when its out.

I have heard this could be the transmission’s coolant vacuum valve. Does this circulate coolant through the transmission? That seems to be the simple fix and makes sense.

I had the transmission serviced, new fluid, filter etc about 6 months ago, but the problem didn't completely resolve. Now with the warmer weather, I'm thinking I should iron out this issue.
I have a durametric scanner, but it only shows alarm fault codes (historic, none present now) to be honest, I am not sure I'm using the durametric to its potential, it seems pretty lame when I do the short test on all modules, so I would welcome advice on this as well.