Service manual

Group 59 Anti-Lock Brake System (Bendix) Troubleshooting

ECU LEDs

The condition of speciﬁc ABS/TCS components is pro-

vided by a series of LED’s on the side of the ECU

housing. If an error condition is detected within the sys-

tem by the ECU, one or more of the LEDs will light to

show the location and component associated with the

fault.

There are ten LEDs plus a magnetically activated reset

switch in the ECU diagnostics. The LEDs are software

driven and are either ON, OFF, or ﬂashing, depending

upon their monitoring function (see ECU Diagnostic

LEDs table page 44).

ECU Diagnostic LEDs

Label Identiﬁes Color Signiﬁes

FRT Steer axle Red Fault detected on a steering axle ABS component or its wiring.

MID Forward drive axle Red Fault detected on a forward drive axle ABS component or its wiring.

RER Rear drive axle Red Fault detected on a rear drive axle ABS component or its wiring.

RHT Right side of vehicle Red Fault detected in a component that is on the right side of the vehicle.

LFT Left side of vehicle Red Fault detected in a component that is on the left side of the vehicle.

TRC Traction control Red Fault detected in an TCS component or circuit.

MOD ABS modulator valve Red Fault detected in an ABS modulator valve or its wiring or with an

ATR-2 traction control valve.

SEN ABS wheel speed sensor Red Fault detected in an ABS wheel speed sensor or its wiring.

ECU ECU electronic controller Red The ECU has detected a failure in its own circuitry.

VLT Voltage supply to ABS Green Indicates that voltage is supplied to the ECU and that the voltage is

in the correct range (11 to 17 VDC). This LED ﬂashes if voltage is

present but out of range.

Diagnosing Faults Using the ECU LEDs

The troubleshooting diagrams and ﬂowcharts in this

section provide a method to help locate a fault that is in-

dicated by the ECU LEDs.

Technicians experienced in troubleshooting Bendix ABS

problems may begin troubleshooting using the quick

reference ﬂow charts on the next two pages. Less expe-

rienced technicians should begin troubleshooting using

the Initial Start-Up Procedure ﬂow chart.

When a fault has been identiﬁed and corrected, reset the

ECU diagnostics by passing a small magnet over the

point labeled RESET on the ECU (the magnet must be

strong enough to pick up a 3 oz. weight). If additional

faults exist, repeat the troubleshooting process.

W5000953