Gearbox in limp mode

Niall Owner/Technician United Kingdom Posted   Latest  
Resolved
Drivetrain
2004 Land Rover Range Rover HSE 4.4L (1 M62) 5-spd (5HP-24)
P0730 — Incorrect Gear Ratio
Limp Mode

2004 Range Rover L322 4.4 BMW ZF5HP24 120k Transmission in D going into limp mode (5th gear). With code (P0730) cleared it will start off in 1M go to 1 then big flare and jolts into 5th. In manual mode will change through gears no thumping or delays, will drop down through the gears when road speed drops but will not change up with higher RPM. Box was 1ltr low in fluid, have dropped pan, nothing in pan and very little on magnets. Removed and bench tested all solenoids EDS1-5 with injector tester, ohms, current ramps and values on Pico look to be good, but 2 solenoids are much quieter when activated than the rest?. MV1-3 activated with battery, ohms and current ramps good, all sound equal. The temperature sensor might be an issue as after an overnight sit it reads 40c with the engine temp reading 16c bringing a plausibility fault. When I topped up the fluid originally I am sure it was working OK. One test I tried was dropping to low box, it will change up and down gears quite well with slight flare in 1st. I read in a post somewhere? that in low box that one of the inputs is not used?.

Hoping one of the transmission experts might shed some light on this.

0
Noel Owner/Technician
New Jersey
Noel
 

The snap ring on the “A” clutch drum is a common failure and can cause this problem. There is an updated clutch drum available.

+2
Ð Awarded
Agree
Helpful
Jared Diagnostician
Maryland
Jared
 

I second this opinion. A clutch is not on in 5th, that's why it defaults to 5th for limp.

+1
Ð Awarded
Timothy Owner/Technician
Wisconsin
Timothy
 

The P0730 is just a generic code for incorrect ratio. If you manually shift these, more than one band is applied, vs. just being in drive, and it usually will ‘cure’ a 1st gear flare because of this. This thing needs a transmission, because the trans shifts with a flare even in low range, which is higher RPMs that when in high range, which means your pump pressure should be higher, thus better…

+1
Ð Awarded
Agree
Niall Owner/Technician
United Kingdom
Niall Delay
 

Thanks for replies guys will have a discusion with customer this week, probably recommend replacement used box.

0
Delay Ð Awarded
Niall Owner/Technician
United Kingdom
Niall Resolution
   

Finally removed and partially stripped this transmission, found no issue with the A Clutch Drum mechanically, but convinced by the replies received I did an air check on the A Drum Piston and found major leak past the smaller of the o'ring's. Due to cost of repair kit and some heavy tooth wear on the intermediate shaft and the availability of a good used unit complete with transfer box for less…

0
Resolution Ð Awarded