2000 R50 not changing gears

[Davus]

Hi folks

 

A bit of an issue has popped up with my sons r50. 2000 model with 311,000 kms on the clock. Australian release with VG33E.

  

Great service history and one owner before we got it. It has seemingly been looked after very well for most of its life. 

 

The car is struggling with gear changes. From a standing start, accelerating easily on flat ground, it will not shift from first to second. In fact it will rev as far as you let it with just very mild throttle without changing gears. 

 

The moment you release from the throttle a touch (not off the throttle completely), it will change gears. When it does change gears the change is normal….not hard.  But it will not change until you release the throttle a tiny bit. 

 

We have changed out the tps for a known good one. And we have done a full trans fluid change (although wasn’t confident that would be the issue). None of those changes made and difference. 

 

I ran the transmission through the diagnostic sequence (so you get the flashes with the O/D OFF light.  I do get the 10 flash sequence which shows 6, 7 and 10 getting slightly longer flashes. 

 

Online searches seem to indicate 

 

Flash 6: Overrun clutch solenoid circuit fault.

Flash 7: Torque converter lock-up solenoid circuit fault.

Flash 10: Line pressure solenoid circuit fault.

 

I haven’t yet dipped into these codes too much, and am not sure if this is showing me historical or current codes……or both. 

 

Before I go too much deeper, I wanted to ask the group if anyone has come across this before, and if so, what was the fix. 

 

Or indeed any suggestions. 

 

Thankyou.

[Davus]

Hi all. 
 

Checking back to see if anyone might have an idea on what might be going on here. I’m a little stumped and my son can’t drive the car as is. 

[Slartibartfast]

I do not have a service manual that I know is correct for an Aus-market R50. This manual covers the US-spec 2000 R50. Hopefully they're largely the same, because that's all I have to work with. Your decoding of the flashes matches what I'm seeing, and the manual has detailed troubleshooting for each of these codes.

 

The troubleshooting for the torque converter lockup solenoid (AT-148) shows its wiring going from the transmission computer, through connector M71/B51, through B64 (labelled "terminal cord assembly"), to a final plug at the solenoid itself. The wiring for the overrun solenoid (AT-188) and the line pressure solenoid (AT-162) go through the same connectors, and the same harness.

 

Three circuit faults, in the same harness, going through the same connectors, makes me suspect a corroded/melted connector or damage to the harness. Unlikely that three solenoids all walked off the job at the same time. I would check the wiring around the gearbox, see if there's an obvious spot where the harness got smashed or something. Failing that, I expect that chasing any of those three troubleshooting procedures will lead you to the cause of the other two.

[Davus]

3 hours ago, Slartibartfast said:

I do not have a service manual that I know is correct for an Aus-market R50. This manual covers the US-spec 2000 R50. Hopefully they're largely the same, because that's all I have to work with. Your decoding of the flashes matches what I'm seeing, and the manual has detailed troubleshooting for each of these codes.

 

The troubleshooting for the torque converter lockup solenoid (AT-148) shows its wiring going from the transmission computer, through connector M71/B51, through B64 (labelled "terminal cord assembly"), to a final plug at the solenoid itself. The wiring for the overrun solenoid (AT-188) and the line pressure solenoid (AT-162) go through the same connectors, and the same harness.

 

Three circuit faults, in the same harness, going through the same connectors, makes me suspect a corroded/melted connector or damage to the harness. Unlikely that three solenoids all walked off the job at the same time. I would check the wiring around the gearbox, see if there's an obvious spot where the harness got smashed or something. Failing that, I expect that chasing any of those three troubleshooting procedures will lead you to the cause of the other two.

 

Thanks very much mate. This response was a great kick start for me. Much appreciated. 

 

I've got a copy of the manual, and have started diving in. I can see the B64 connector under the car, and will start by doing some resistance measurements on the solenoids. 

 

I agree that is seems odd that those three solenoids would "walk off the job" (I'll be using that saying again in the future" at the same time. 

 

Ive also confirmed through DataScan that the TPS is calibrated correctly - showing .5V when closed, and 4.0V at WOT - this is a known working TPS. 

 

Thanks again - and hopefully ill be able to report back soon with the fix. 

 

 

[Davus]

Hi all,

Another update on this one. I’ve now spent quite a bit more time going through the factory workshop manual and testing things properly.

The symptom is still exactly the same. From a standing start it will hold first gear under even fairly light throttle and just keep revving. The moment I ease off the throttle slightly, it shifts cleanly into second.

The same basic behaviour then happens again on the 2-3 shift — it will hold the lower gear until I back off slightly, then it shifts normally. The actual shifts themselves are smooth.

So far I’ve checked the following:

• TPS has been replaced with a known-good unit, and DataScan shows a smooth signal from roughly 0.5V closed to around 4.0V WOT.
• Transmission fluid has been changed.
• All five solenoids are within factory resistance spec:
  • Line pressure: 3.4Ω
  • TCC: 13.6Ω
  • Shift A: 25.0Ω
  • Shift B: 25.4Ω
  • Overrun: 24.8Ω
• All five solenoids respond when 12V is applied directly. This was a bit of a challenge given I had to put my ear against the transmission sump to hear some of them:
  • Red — line pressure solenoid: clicked, but not particularly loudly
  • Blue — TCC solenoid: noticeable click
  • Green — shift solenoid A: very quiet click
  • Yellow — shift solenoid B: very quiet click
  • Grey — overrun clutch solenoid: very quiet click
• Wiring from B64 back to the TCM measures around 0.2–0.3Ω on all five relevant circuits, so the external harness looks good between the B64 connector and the TCM.

I’m not keen to start opening up or pulling out the transmission until I’ve exhausted everything I can reasonably check externally first.

 

I’d really appreciate any guidance if anyone has seen similar behaviour or has anything else they think is worth checking before I go any deeper.

Thanks.