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Parking brake module

13460 Views 5 Replies 3 Participants Last post by  smurtaza
Is the parking brake module interchangeable between RRS L320, LR3, LR4 and L322 full size RR?

I'm getting C1A00-4B control module system internal failure - over temperature error. Removed the module and ran the motor manually (connecting 12V). Motor works fine and pulls/pushes the cables but draws too much current (over 30AMPS) and trips the fuse on 12V testing unit (after 2-3 sec). I don't know if the problem is the transmission unit or the motor itself.

So want to buy a used module as new is around $900+. There are some good used ones available from L322 and just wondering if it's the same unit as L320.

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...Motor works fine and pulls/pushes the cables but draws too much current (over 30AMPS)...
It very much sounds like this is your actual problem, not the brake module. The brake module is apparently not malfunctioning, just temporarily overheating because of the unusually high current passing through it, and shutting down to protect itself.

Motors draw current equivalent to the load they are under, even until they overheat/melt. It very much sounds like whats really happening is increased mechanical resistance around the operation of the parking brake (ie your parking brake is clogged with dirt or something), which is forcing the motor/actuator to work much harder, so in turn its drawing far more current, which is in turn making the control module overheat.

You need to find/fix the root cause of the motor drawing such high current and don't operate the motor again even with a test box until you know for sure that the brake mechanism is at least mechanically free to operate properly, otherwise you risk damaging/burning out the motor, wiring, and/or the control module.
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Thanks for the reply justniz, I actually ran the motor with cables disconnected (out of the car). So there is no load on the cables, motor runs just fine and sounds okay as well, but for some odd reason draws too much current. May be it's the gear box/transmission that is putting up the resistance.
Update. Since motor was drawing too much power, took the module apart, removed the motor from transmission unit, opened one side of the motor and found it all gunked up with black stuff. Cleaned the motor with brake cleaning fluid, put it back together, tested and put it back in the module. Tested motor with transmission and cables attached and now it works great. It only draws 10 Amps as oppose to over 30 Amps before the cleanup. Going to put the module back in the car and adjust the brake shoes. Hopefully it'll all work fine.
Wow that is impressive. Did you have the truck on a lift or was this a total driveway operation? Was it easy to access the Motor system and about how long did it take? Good job.
I do have access to a lift and it took couple of hours to remove the module. It is pretty tight in there but I believe it could be done on a driveway, if you put RR on extended height. But to release the cables you need to remove the rare brake rotors and for that back wheels have to come off. Most time was spent on removing rotors, releasing cables from left/right shoes, emergency cable under the shifter area and just removing all the hangers to get the cables free. Module comes out from the passenger wheel arch.

I have seen a youtube video of a guy taking the module cover off while still in the car but I was not able to get to the screws on the cover (space was too tight) I think he was working on LR3 (may have more space on LR3). Plus the module cover is glued on and even after getting it out, it took some effort to pry it off. I don't think I would have been able to get the cover off while on the car, even if I got the screws off.

Once the module is out of the car, you can unscrew and pry the cover off. To test the it, unplug the motor connections and you can test the mechanism by providing 12V to the motor connections. Be careful, a straight battery connection provides up to 600+ AMPS and could run the motor really fast and pull the cables to the stop and break the transmission. I used a testing tool that puts out 30-50 AMPS and trips on anything over that power.

Reversing the polarity runs the motor in reverse, so you can play with it pulling and pushing the cables. There is a youtube video showing how to remove the cables from the pulling mechanism and remove the motor/transmission out of the module (not every hard to do). Opening up the motor was the hardest part and I was not sure if that would even work. Back cover of the motor has crimped tabs that had to be pried to get the back cover off. Putting it back on was pretty easy.

Putting the transmission cogs back in the right order was a little challenging but not too bad. The whole module fix took around 2 hours.

I now have another issue to deal with. After removing the brake module, (with the module out) I tried to start the car and now I have flashing hazards, bunch of errors (transmission failure, transfer case errors, etc...) and no start. I hope putting the module back will sort the issues, otherwise I believe there are some wires in the back that sometimes get shorted out and RR computers go nuts (battery is putting out 13+ Volts). Will cross that bridge when I get there.

But at least now I know how the parking brake mechanism works and what are the things that could go wrong it with.
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