jc99
Well-Known Member
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- #1
I have been fighting poor braking on my 2021 JTRD 3.0 since I bought it and mostly accepted it just had crappy brakes. Originally I would notice that when I started to skid and the ABS would actuate the pedal would sink to the floor immediately but still brake. I brought this to the dealer and they came back with brakes are normal and that is how it operates. I have caught them with other stories so didn't really believe them but left it alone as I was dealing with a bunch of other problems with them already.
I'm not sure why but in the last while the brakes got worse or I had more incidents where I had to slam on the brakes and the pedal sunk to the floor. I decided it was time to dig a bit deeper and work on resolving it before I look at a full brake upgrade.
So far I have done probably 10 pressure bleeds and 6-8 full ABS bleeds using jscan.
I have also replaced the master cylinder (which was bench bled) and done standard pressure bleeds, pedal pump bleeds and abs bleeds after installing the master cylinder. So much wasted brake fluid! None of this has resolved the issues.
Here is a list of what I am experiencing:
-Engine OFF pump pedal and hold - Pedal holds it's position no matter how hard you press it.
-Engine running, stationary - Light to medium pedal force, pedal holds in place
-Engine running, stationary - pedal slowly sinks under very hard sustained pressure. If you pump it a couple times it gets hard again and then slowly sinks to the floor as well with firm pressure over maybe 10-15 seconds.
-Driving with ABS enabled - As soon as the ABS kicks in (extremely hard braking) the pedal immediately drops near the floor while continuing to pulsate. It is really unnerving as this happens even though the brakes continue to work.
-Driving with ABS disabled- If you try to skid the pedal very slowly sinks during extended hard braking eg from very high speed, however the braking feel more confident then with the abs enabled.
From what I have surmised at this point, it's likely the ABS HCU which has many valves and bypasses within in it that is likely causing the issues.
I think there are two parts to the ABS unit and am not sure if 68502584AD includes them both (need to clarify it with whomever I buy it from)
https://www.mymoparparts.com/oem-parts/mopar-anti-lock-brake-system-module-68502584ad
-Electronic control portion
-Hydraulic portion
One other thing to note is I have the Advanced Safety Group (Adaptive Cruise Control and the collision warning radar) so the unit is able to actuate the brakes itself for autonomous braking.
I think my next step is to replace that ABS HCU module but wanted to check and see if anyone has done this and if it resolved their issue. My thought is there must be a bad valve in the unit that is letting fluid slip through and when the ABS actuates the valve is causing even more issues hence the pedal falling so fast.
I could also cap the master output ports to confirm I didn't just get a bad new master and that fluid is bypassing within it but I don't think this is the problem since there was no change with the new master I installed.
I could also cap the current HCU (4 lines going to the calipers) to be sure there is not something else going on down the lines but I don't think this is really possible with the symptoms I am seeing.
Any thoughts or solutions others have had would be great to hear before I get back into buying parts and rebleeding everything.
Also wondering if anyone has replaced their ABS module and used Jscan to code it to the jeep.
I'm not sure why but in the last while the brakes got worse or I had more incidents where I had to slam on the brakes and the pedal sunk to the floor. I decided it was time to dig a bit deeper and work on resolving it before I look at a full brake upgrade.
So far I have done probably 10 pressure bleeds and 6-8 full ABS bleeds using jscan.
I have also replaced the master cylinder (which was bench bled) and done standard pressure bleeds, pedal pump bleeds and abs bleeds after installing the master cylinder. So much wasted brake fluid! None of this has resolved the issues.
Here is a list of what I am experiencing:
-Engine OFF pump pedal and hold - Pedal holds it's position no matter how hard you press it.
-Engine running, stationary - Light to medium pedal force, pedal holds in place
-Engine running, stationary - pedal slowly sinks under very hard sustained pressure. If you pump it a couple times it gets hard again and then slowly sinks to the floor as well with firm pressure over maybe 10-15 seconds.
-Driving with ABS enabled - As soon as the ABS kicks in (extremely hard braking) the pedal immediately drops near the floor while continuing to pulsate. It is really unnerving as this happens even though the brakes continue to work.
-Driving with ABS disabled- If you try to skid the pedal very slowly sinks during extended hard braking eg from very high speed, however the braking feel more confident then with the abs enabled.
From what I have surmised at this point, it's likely the ABS HCU which has many valves and bypasses within in it that is likely causing the issues.
I think there are two parts to the ABS unit and am not sure if 68502584AD includes them both (need to clarify it with whomever I buy it from)
https://www.mymoparparts.com/oem-parts/mopar-anti-lock-brake-system-module-68502584ad
-Electronic control portion
-Hydraulic portion
One other thing to note is I have the Advanced Safety Group (Adaptive Cruise Control and the collision warning radar) so the unit is able to actuate the brakes itself for autonomous braking.
I think my next step is to replace that ABS HCU module but wanted to check and see if anyone has done this and if it resolved their issue. My thought is there must be a bad valve in the unit that is letting fluid slip through and when the ABS actuates the valve is causing even more issues hence the pedal falling so fast.
I could also cap the master output ports to confirm I didn't just get a bad new master and that fluid is bypassing within it but I don't think this is the problem since there was no change with the new master I installed.
I could also cap the current HCU (4 lines going to the calipers) to be sure there is not something else going on down the lines but I don't think this is really possible with the symptoms I am seeing.
Any thoughts or solutions others have had would be great to hear before I get back into buying parts and rebleeding everything.
Also wondering if anyone has replaced their ABS module and used Jscan to code it to the jeep.
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