Thread: What happened to your D3/D4 today?

Well, it did it again today, 3rd time in as many years.

Drove to the city, (about 20 klms), parked for 2 hrs. Took off down the street and it wouldn't change out of first gear. I was in "D". So without stopping I shifted into "S" mode and the trans immediately shifted up and behaved perfectly.

On other Forum discussions re servicing 6 speed ZF's, guys have mentioned 'mechatronics' and other items they renew/refresh on the 6 speeders. Is there anything on the 8 speeders which require periodic replacement/servicing and which could cause this issue?

Thinking about it, I was in Reverse prior to selecting Park, then switching off. I wonder if that is significant?

Oil has been changed at roughly (without me looking up my records) 104,000 and 148,000 klms, but it cannot be associated with oil otherwise it wouldn't come right simply by shifting to "S" mode. Current klms 156,000

Sounds like an electrical 'solenoid' problem if such a thing exists in an 8 speed ZF???? I'll have to read up about them.

I'm not too fussed about it as I know how to fix it, however on the odd occasions my wife drives it I can fore see an over rev and engine destruction............

Originally Posted by Discodicky

Well, it did it again today, 3rd time in as many years.

Drove to the city, (about 20 klms), parked for 2 hrs. Took off down the street and it wouldn't change out of first gear. I was in "D". So without stopping I shifted into "S" mode and the trans immediately shifted up and behaved perfectly.

On other Forum discussions re servicing 6 speed ZF's, guys have mentioned 'mechatronics' and other items they renew/refresh on the 6 speeders. Is there anything on the 8 speeders which require periodic replacement/servicing and which could cause this issue?

Thinking about it, I was in Reverse prior to selecting Park, then switching off. I wonder if that is significant?

Oil has been changed at roughly (without me looking up my records) 104,000 and 148,000 klms, but it cannot be associated with oil otherwise it wouldn't come right simply by shifting to "S" mode. Current klms 156,000

Sounds like an electrical 'solenoid' problem if such a thing exists in an 8 speed ZF???? I'll have to read up about them.

I'm not too fussed about it as I know how to fix it, however on the odd occasions my wife drives it I can fore see an over rev and engine destruction............

At the risk of unintentionally treating you as stupid, you didn't by any chance do my trick and just touch one of the gear selection paddles by mistake?

Originally Posted by gavinwibrow

At the risk of unintentionally treating you as stupid, you didn't by any chance do my trick and just touch one of the gear selection paddles by mistake?

Thanks, good point but am pretty sure I didn't, but it's worth a strong consideration!!

PS: you wouldn't be the first person to 'accuse' me of being stupid...

I might try that tomorrow morning as I'll be doing exactly the same trip/duration. (coffee with some retired mates).

Originally Posted by gavinwibrow

At the risk of unintentionally treating you as stupid, you didn't by any chance do my trick and just touch one of the gear selection paddles by mistake?

Yep, guilty of that.

Any fault codes? Usually a failure to shift means that either not enough line pressure in the valve body, or a dirty solenoid that doesn't actuate fully, allowing the clutch pack to release.

Your 8 speed is essentially a hydraulic coupling (the torque converter) and an 9 cog fluid filled gearbox, fitted to a valve block with 9 solenoids, one for each gear and one for reverse. Transmission fluid flows thought the valve body,pressure and flow is controlled by the mechatronic ( its brain) and managed by the solenoids at the end of each line.

Cleanliness and correct fluid level is key. Common issues are wear in the valve lines and fluid pressure loss, or bypass.

Shifting to sport increases the line pressure, so your issue tells me that perhaps the 1st gear solenoid may be dirty or partially blocked, limiting flow and preventing a shift to the next gear. Sport mode overrides the standard pressure, but doesn't solve the issue.

Removing the valve body and checking the solenoids plus a full fluid flush and replacing the valve body to transmission housing pump seals are some of the things that can be done to resolve this.

Originally Posted by Eric SDV6SE

Any fault codes? Usually a failure to shift means that either not enough line pressure in the valve body, or a dirty solenoid that doesn't actuate fully, allowing the clutch pack to release.

Your 8 speed is essentially a hydraulic coupling (the torque converter) and an 9 cog fluid filled gearbox, fitted to a valve block with 9 solenoids, one for each gear and one for reverse. Transmission fluid flows thought the valve body,pressure and flow is controlled by the mechatronic ( its brain) and managed by the solenoids at the end of each line.

Cleanliness and correct fluid level is key. Common issues are wear in the valve lines and fluid pressure loss, or bypass.

Shifting to sport increases the line pressure, so your issue tells me that perhaps the 1st gear solenoid may be dirty or partially blocked, limiting flow and preventing a shift to the next gear. Sport mode overrides the standard pressure, but doesn't solve the issue.

Removing the valve body and checking the solenoids plus a full fluid flush and replacing the valve body to transmission housing pump seals are some of the things that can be done to resolve this.

Or, as suggested above, paddle was tripped and it was in manual change mode, a far more likely outcome.

Originally Posted by DiscoJeffster

Or, as suggested above, paddle was tripped and it was in manual change mode, a far more likely outcome.

If you are are looking for it, does the dash tell you when you've done that?

Originally Posted by BradC

If you are are looking for it, does the dash tell you when you've done that?

Yes, the D is replaced by the gear you are in. If you touched the left paddle at idle, it will drop to 1 as I think it normally settles on 2 at idle or startup. But the first post said the car was in Drive so I took this as being observed rather than assumed.