Hybrid Escape ABS DTC's

[Mekanik]

I’m working on a 2006 hybrid Escape. The concern is that intermittently the brake pedal will go to the floor and the vehicle is hard to stop. I did a self test of the ABS module and I had three DTC’s: C1479, C1481, and U2023. There is not even a pinpoint test for the C1479, C1481 DTCs. The shop manual just says to replace the HCU/ ABS module if the codes come back, which they did. C1479, C1481 are plausibility faults indicating a difference in expected pressure, typically a result of a hydraulic problem. The U2023 is a network DTC. Well this seemed simple enough, so I replaced the HCU/ABS module and performed the arduous task of bleeding the new HCU.

One week later and 200 miles the vehicle is back with the same concern and the same DTC’s, and I noticed something strange on the oasis report that I didn’t notice a week earlier. This vehicle had a HCU/ABS module replaced at another dealer for the SAME DTC’s one year ago. I contacted hotline and they really weren’t much help. I’ve talked to three engineers there and they all tell me something different. One engineer told me that the rear brakes hanging up could cause this and if they are okay then replace the master cylinder. I did go through the rear brakes and they are as free as a bird right now but the problem happened again.

Another engineer tells me that the master is split diagonally and a failed master would never cause two codes for the rear brakes. I was visited by an FSE yesterday, and this is where is gets REALLY bad. The FSE tells me how unusual it is for a vehicle like this to need three HCU’s and I correct him, telling him it’s only had two. The reason he knows this is because he went out to another dealer for THIS vehicle for the SAME problem with the SAME DTC’s!!!

At THAT time he recommended a replacement of the HCU and the wiring harness because the connector that plugs into the HCU had brake fluid on it. Well I checked that and it’s dry as a bone just like the connectors under the master cylinder that I suspected might be contaminated with brake fluid.

The FSE left yesterday without giving me any direction to go in. He’s going to get back to me after doing some research. One thing that’s got me thinking is the U2023. The FSE tells me the network being down won’t cause the other DTC’s, but I’m thinking of maybe overlaying the network. When I did the bleed procedure I really didn’t have any problems other than the master cylinder cap leaking. When it would have me bleed the LF front caliper fluid would come out of the LF caliper, and the same thing for the other calipers. This makes me believe that I do have the lines in the correct position. Besides, this truck will go 200 miles without setting any DTC’s.

Does ANYONE have any ideas on this one???