My Jeep Compass Forum banner
1 - 3 of 3 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
My compass trailhawks battery was completely dead a few weeks back. Doors wouldn’t even unlock. Put a brand new battery in and the same thing happened. Probably the alternator but I just bought this keep in October so I’m not really sure.

any ideas?
 

·
Registered
Joined
·
1,430 Posts
If you have a second gen (2017.5+), your car has two batteries, did you change them both? The auxiliary battery is right in front of the main battery, but is quite a bit smaller. It seems to be responsible for most electronics, while the large battery is mostly for cranking the motor. We don't have precise specs on which battery runs what in the car, all I can tell you is you definitely need both of those batteries to be healthy to have a working car.

A large relay called the PCR (Power Control Relay) connects the two batteries in parallel under certain circumstances for charging conditions, and disconnects them from each other under other circumstances such as engine startup cranking. If the battery that runs the PCR is dead you might have that dead electronics condition.

You can try jumpering the relay like this (but you should use a heavier gauge wire than the one in this photo) to see if it brings the electronics online, and you can try testing the voltage of each and charging them if you have a charger. If that aux battery was not replaced you need I believe a "Group 400" battery such as the "Deka AUX14 Auxiliary Battery" or like this one from Napa: https://www.napaonline.com/en/p/NBPAUX14

15322
 
1 - 3 of 3 Posts
Top