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Discussion Starter · #1 · (Edited by Moderator)
The car actually runs but the transmission shift actuator doesn't work so before I got pull the unit out I want to make sure it is getting power and ground to all the right places. have power at the column switch and the dash indicator just illuminates the P and does not shift.

Moderator note: Author noted previously that battery cables were attached backwards, but car now starts and runs with battery connected correctly.
 

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Look for the reset switch before you "pull" anything in an attempt to fix the problem. Your car has electrically assisted shifting. Most of the current pulled when moving the shift lever is from Park to N to Drive. Read the OM and look for the breaker on the fuse panel.
What condition is the battery in? Last replaced?
 

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No circuit breaker on the Turbo R, just a single fuse. F2, fuse A6. It is possible the diodes in the shift actuator relays have blown. They are located inside the shift actuator housing. Before taking it apart just check for continuity on the pins of the housing connection plug when you shift the lever through all positions.
 

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Discussion Starter · #5 ·
Thank you for the information and part of why I am in search of wiring diagram for that. Have spent most of my morning looking for it. Sorry I am more used to simple cars that aren’t over complicated.
 

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Discussion Starter · #7 ·
So far what I have seen about the electric shift module is that it has an electric motor which turns a shaft that is hooked to the shift linkage on the transmission which is controlled but the shifter assembly on the steering column and the only fuse I can find for power is B1 which is a 20a fuse. I am getting battery voltage at the column and it is sending a signal to the connector that goes to the module but what power source does the electric motor use? I really don’t want to pull it out and apart if I don’t have to.
Cloud Automotive fuel system Vehicle Automotive tire Hood
 

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The power for the actuator comes from the shift lever contacts, so if you check for continuity on the pins of the housing connection plug when you shift the lever through all positions you should get voltage on a series of pins that will power the motor. It is a servo motor, so it only turns a small amount to shift gears. There are several microswitches and relays inside. The actuator and wiring will be the same as a Rolls-Royce Silver Spirit or Spur of the same year, and a wiring diagram from www.rrtechnical.info will show the circuit. Go there, click on '005 Silver Spirit and Bentley Mulsanne. 1987 - 1989 Model Years 20,000 Series Supplement Workshop Manual TSD4701 Electrical' then '23 Electric Gearchange' and the wiring diagram will be there. Somewhere in the manual it will show how to dismantle it for repair. It may not be under that section, you may have to open the section going back to an earlier year in the manuals to find it. There might be more info on the 1990 model year at the Bentley Heritage site or you might have to get a copy of IETIS which is the electronic workshop manual that they changed to about 1990. I think the wiring for the 1990 gear actuator is basically the same as 1988 - 89 though..
 

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Look for the reset switch before you "pull" anything in an attempt to fix the problem. Your car has electrically assisted shifting. Most of the current pulled when moving the shift lever is from Park to N to Drive. Read the OM and look for the breaker on the fuse panel.
What condition is the battery in? Last replaced?
The car actually runs but the transmission shift actuator doesn't work so before I got pull the unit out I want to make sure it is getting power and ground to all the right places. have power at the column switch and the dash indicator just illuminates the P and does not shift.

Moderator note: Author noted previously that battery cables were attached backwards, but car now starts and runs with battery connected correctly.
Hey hey. Be suspect of the battery and the ground first no matter what. Clean the battery terminals, clean the ground contact and try a different battery. Shift problems are almost always bad, low or disconnected battery. Good luck. Rollsroycerescue.

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