ABS Codes

[phatboi1981]

I pulled the abs codes on my 94 eddie 4x4 today.The codes are 44,41,54and 75. any ideas on what they are?

 

[Iron Weasel]

I pulled the abs codes on my 94 eddie 4x4 today.The codes are 44,41,54and 75. any ideas on what they are?

41 - Front Left Sensor Mismatched Output

44 - Couldn't find.

54 - Couldn't find.

75 - Front Left Sensor Erratic Output

Codes 35, 41, 55, and 75 are generated by the ECU's detection of a missing, erratic, or otherwise improper wheel speed signal from the left front wheel speed sensor. The codes are set for specific faults at various vehicle speeds that are as follows:

* Code 35: ECU detects that the front left wheel speed information is erratic. This code is only set at vehicle speeds greater than 25 mph.
* Code 41: ECU detects that the front left wheel speed information does not match the right front and rear axle wheel speed information. This code is only set at vehicle speeds greater than 12 mph.
* Code 55: ECU detects that the front left wheel speed signal has dropped out when it was previously there. This code is not dependent upon vehicle speed.
* Code 75: ECU detects that the front left wheel speed information is erratic. This code is only set at vehicle speeds greater than 12 mph and less than 25 mph.
* Codes 35, 41, 55 or 75 can not be set with the vehicle stationary. The vehicle should be driven when attempting to duplicate the concern.
* If Codes 35, 41 or 55 are set, then the ABS warning lamp will come on and will remain on until the vehicle is shut off. If only Code 75 is set, the ABS warning lamp will come on. However, if the condition is corrected, the ABS warning lamp will be turned off by the ECU and the system will again be operational.

NOTE: In most cases, Code 75 will be accompanied by Code 35.

POSSIBLE CONTRIBUTING COMPONENT/VEHICLE WIRING CONCERNS

* Damaged/missing tone ring teeth or missing tone ring
* Air gap too small or too large
* Excessive axle vibration
* Weak sensor
* Loose sensor
* Intermittent short or open in Circuit 521 (T/O) or 522 (T/BK)
* Disturbances caused by ignition or Radio Frequency Interference (RFI)
* Defective trigger circuit in ECU

 

[Vargas]

Iron Weasel, that's great info. I also have a '94 EB. Any info on codes 17,22,23,24,25,26?

 

[Iron Weasel]

Iron Weasel, that's great info. I also have a '94 EB. Any info on codes 17,22,23,24,25,26?

17 - Reference Voltage

Code 17 is generated by the ECU indicating a loss of system reference voltage.

POSSIBLE CONTRIBUTING COMPONENT/VEHICLE WIRING FAULTS

* 30 amp fuse open
* Intermittent connections to battery, main relay or ground
* Main relay coil or contacts open
* Open or short to ground in Circuit 532 (O/Y)
* Open or short to ground in Circuit 599 (PK/LG)
* Open or short to ground in Circuit 601 (LB/PK)
* Short to ground through valve block
* Intermittent valve failures
* High resistance valves

If Code(s) 22, 23, 24, 25, 26, or 27 have also been obtained along with Code 17, an intermittent valve or valve wiring fault is indicated.

* Disconnect the 8-pin connector from the HCU.
* Measure resistance between the following on the component side of the 8-way:



NOTE: Refer to the above Mini-Schematic for valve block pin designations.

* Pin 1, Pin 4 and Pin 2 - (RA Inlet)
* Pin 1, Pin 4 and Pin 3 - (RA Outlet)
* Pin 1, Pin 4 and Pin 5 - (FR Outlet)
* Pin 1, Pin 4 and Pin 6 - (FL Inlet)
* Pin 1, Pin 4 and Pin 7 - (FL Outlet)
* Pin 1, Pin 4 and Pin 8 - (FR Inlet)
* All inlet valves should be 5-8 ohms .
* All outlet valves should be 3-6 ohms . A drive over rough road is recommended while the resistance is being monitored.

NOTE: Valve resistances causing this problem tend to fluctuate rapidly. Another person to monitor resistance while the first drives is highly recommended.

* Does the resistance on any valve move out of specification at any time?

YES -- High or low valve resistance detected. Replace HCU.

NO --
* Measure resistance between the following on the component side of the HCU 8-pin connector:
* Pin 1 and valve block.
* Pin 4 and valve block.
* A drive over rough road is recommended while the resistance is being monitored.

NOTE: Valve resistances causing this problem tend to fluctuate rapidly. Another person to monitor resistance while the first drives is highly recommended.

* Is the resistance measured less than 10M ohms at any time?

YES -- Replace HCU.

NO --

* Jumper Breakout Box Pin 19 to Pin 1 or Pin 14.
* Set up DVOM to measure voltage between Breakout Box Pins 17 and Pin 1 or Pin 14.
* A drive over rough road is recommended while the voltage is being monitored.
* Does the voltage fall below 9.5V at any time?

YES -- Find and Repair source of high resistance or open in one of the following: Circuit 532 (O/Y) between HCU and System Relay. Circuit 537 (T/Y) between battery and System Relay.

NO -- Conclude Intermittent Diagnosis



EDIT:

While the most likely problem is the HCU took a dive on you, you should still check out the wiring just to rule it out. I checked a few places to see how much a new Hydraulic Control Unit (HCU) will run, and for a re-manufactured unit, you're looking at almost $1,000 from Rockauto. If you need any additional diagrams or pin-outs, let me know and I'll get them to you ASAP.

 

[Vargas]

First thing I am going to do is replace the ABS relay. My ABS light has the somewhat common symptom of no trouble light after being parked overnight, but nearly always turns on and stays on when starting after being recently driven. Most people who experienced this pattern fixed it by replacing the relay.

 

[Iron Weasel]

Start simple and work your way up to more complicated things.

 

[phatboi1981]

all fixed but when i push the brakes to the floor i get a vibration and a *grinding* like sound any aideas on that?
and thx for the info i replaced the sensor and the abs light went off
(except when the vibration and grinding sound begins)