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Hi I am new to forum. I have purchased a 1998 range rover p38 4.6 hse with 135k on it. It has a check engine light on snd seems to be stuck in 3rd gear as well as a clicking noise coming from the becm. I ran the code and it came back p1777. I erased the code and it came back again. I checked the transmission plug located behind the driver side head it seemed to be in good condition. I have an extra transmission controller but haven't installed it As well as access to a spare becm . I am unsure what my next steps should be. Any help or advice is greatly appreciated. Thanks in advance.
 

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1995-2002 Range Rover P38A
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Hi I am new to forum. I have purchased a 1998 range rover p38 4.6 hse with 135k on it. It has a check engine light on snd seems to be stuck in 3rd gear as well as a clicking noise coming from the becm. I ran the code and it came back p1777. I erased the code and it came back again. I checked the transmission plug located behind the driver side head it seemed to be in good condition. I have an extra transmission controller but haven't installed it As well as access to a spare becm . I am unsure what my next steps should be. Any help or advice is greatly appreciated. Thanks in advance.
Don't I hate the post that has codes but no descriptions?
Anyway P1777 is a gearbox ignition retard request line fault.
This is a 12 volt PWM signal from the EAT (transmission) ECU to the ECM (engine control module) requesting spark retard for smooth transmission shifting. You may want to check continuity of wire from the pin 32 at EAT ECU to the pin 31 in connector C507 at engine ECM.

If wire has continuity, then you can check voltage from the pin 32 at EAT ECU to the body ground during transmission shift after clearing the code. If you don't have any voltage, EAT ECU is suspect.

If wire has no continuity, run a temporary wire from the two points and see what happens after clearing the code.

Good luck!
 

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Thanks for the info and sorry for no description of the code. I will check these things tomorrow afternoon and post my findings
 
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