How can I disable the HCU electrically?

My HCU randomly comes on (94 Mark 8). I hear a rumble and feels like the car slows just a little bit. I disconnected the sensors and it is still happening. I'm guessing it's the HCU but I don't know how to disable it to see if the problem goes away. Does anyone know how this can be done or have any troubleshooting advice? The trac assist button lights up off all the time and will not switch to on. Thanks for you help.

Tim

RE: How can I disable the HCU electrically?

In the power distribution box under the hood, fuse 9 protects the anti lock brake system, and fuse 13 protects the ABS motor. If you pull these, the ABS system probably won't work.

I think it would be better to just read the ABS codes though..

RE: How can I disable the HCU electrically?

OK. Thanks for the advice. I will check the codes, or shoudl I say, have them checked since I don't know how to check them.

RE: How can I disable the HCU electrically?

It's easy:

Open the hood and then open the little door above the passenger side headlight. In there you'll see a red cover for the ABS test plug. Push the clip fprward and push the plug down to remove it from the red cover. Hold the plug facing you with a row of 2 terminals on the top and 4 terminals on the bottom. Take a jumper wire and put one end in the third from the left terminal on the bottom row of 4. Connect the other end of the wire to ground or the negative battery terminal.

Then just turn your key to the run position and count the flashes of the ABS light. You should get 2 groups of flashes that correspond to the list of codes below. Mine turned out to be a bad wheel sensor.


11 - ABS Module
12 - Electronic Controller-Replacer
17 - Reference Voltage
18 - Isolation Valve No. 1
19 - Isolation Valve No. 2
21 - Main Valve
22 - LH Front Inlet Valve
23 - LH Front Outlet Valve
24 - RH Front Inlet Valve
25 - RH Front Outlet Valve
26 - RH Rear Inlet Valve
27 - RH Rear Outlet Valve
28 - LH Rear Inlet Valve
29 - LH Rear Outlet Valve
31 - LH Front Sensor
32 - RH Front Sensor
33 - RH Rear Sensor
34 - LH Rear Sensor
35 - LH Front Sensor
36 - RH Front Sensor
37 - RH Rear Senson
38 - LH Rear Sensor
41 - LH Front Sensor
42 - RH Front Sensor
43 - RH Rear Sensor
44 - LH Rear Sensor
45 - LH Rear Sensor
46 - RH Front Sensor
47 - RH and LH Rear Sensors
48 - Any 3 Sensors Missing
51 - LH Front Outlet Valve
52 - RH Front Outlet Valve
53 - RH Rear Outlet Valve
54 - LH Rear Outlet Valve
55 - LH Front Sensor
56 - RH Rear Sensor
57 - RH Rear Sensor
58 - LH Rear Sensor
61 - FLS Circuits -or- FLI and PWS Circuit
62 - Travel Switch
63 - Pump Motor Speed Sensor
64 - Pump Motor Pressure
67 - Pump Motor Relay
71 - LH Front Sensor
72 - RH Front Sensor
73 - RH Rear Sensor
74 - LH Rear Sensor
75 - LH Front Sensor
76 - RH Front Sensor
77 - RH Rear Sensor
78 - LH Rear Sensor
88 - Electronic Controller
99 - Electronic Controller

Edit: I moved this to the Brake section.