[Jcpilot9359]

Has anyone seen a code 91 after changing the rear differential fluid? Not sure if they are related but it seems suspicious.

 

[skelley521]

What year and model do you have?
How did you get the code?
Is there any more digits follow the 91?

 

[skelley521]

Quick glance at the 09-12' FSM shows that a generic 91 code could be:

Right front tire pressure sensor internal error
VSA System
Fuel Tank Pressure Sensor

Depending on the system affected. A more specific code would help determine the problem unless I'm missing something.

 

[Jcpilot9359]

2008 Ridge 105k miles. Code came off a reader plugged into the OBD port. The full code read:

91 ABS Controller area network communications malfunction.

 

[skelley521]

Are you getting any other 2 digit codes?
Do you have any dash lights on as well?
.

 

[skelley521]

91 is a F-CAN communication, ABS off, ABS system indicator OFF, VSA On, VSA activation indicator ON
The FSM says to trouble shoot all other codes first.
Then for a example, if you were down to a 68 & 91
Since 68 is a Brake Pedal Position Switch and 91 is a communication issue between.
If you only have a 91 code then here are some pics of steps for you to chew on.
There are more steps, but I would prolly just clear and see if it comes back, just me though.
.

 

[Jcpilot9359]

Thanks for the detailed troubleshooting info skelley521. I cleared the codes but I have not driven it since. I'm doing a lot of commuting and I have a rental car for a while.

 

[speedlever]

I think I would disconnect the battery for a while and "reboot" the RL.

Might be worth a shot.

Also, how old is your battery? We've seen many odd things occur when the battery starts to go south, even though it can still crank the RL.