Brakes - Intermittent or Current ABS Code 61
NUMBER: 93-T-71CORP.REF.NO: 315006R
DATE: June 1993
SECTION: 5
SUBJECT:
INTERMITTENT OR CURRENT ABS CODE 61
- REPLACE ABS PUMP RELAY
MODELS/YEARS:
1991-93 NINETY EIGHT AND 1992-93 EIGHTY EIGHT MODELS
Some 1991-93 Ninety Eight and 1992-93 Eighty Eight models with ABS (Antilock Brakes) may experience an interminent ABS code 61.
This condition may be due to a faulty ABS pump relay. During self test the EBCM/EBTCM (Electronic Brake Control Module/Electronic Brake And Traction Control Module) grounds the coil side of the pump relay and immediately expects to see greater than 500 mv AC feedback voltage from the pump motor run sensor within the PMV (Pressure Modulator Valve) assembly. If the condition is intermittent, the diagnosis in the service manual, Chart F in Section 5E1, will not detect this condition because the pump may run during the bleed procedure which may incorrectly lead to replacing the EBCM/EBTCM.
To diagnose and repair an intermittent code 61 use the following procedure:
1. Visually inspect and ensure good terminal contact of the LH Maxifuse 1 in the underhood fuse block, the ABS main relay, and the 4-wire PMV connector C2.
2. With ignition off, disconnect PMV connector C2, measure resistance from pin E (harness side) to the battery negative terminal.
^ Should be less than 1 ohm. If not, repair high resistance on circuit 151 or clean G102.
3. Measure resistance from pin D (PMV side) to F (PMV side).
^ Should be 10-40 ohms. If not, replace PMV.
4. Measure resistance from pin D (PMV side) to the valve block case.
^ Should have no continuity. If you have continuity, replace PMV.
5. Disconnect ABS pump relay, measure resistance from pump relay cavity 4 (harness side) to PMV connector C2 pin A.
^ Should be 0.2 ohms or less. If not, repair open or high resistance in circuit 850.
6. With ignition on, measure voltage from pump relay pin 4 (harness side) to chassis ground.
^ Should have 0v. If you have voltage, repair short to voltage on circuit 850.
7. With ignition off, connect pin out box, measure resistance from pin 15 to pin 1.
^ Should have no continuity. If you have continuity, repair short to ground on circuit 854.
8. Measure resistance from pin out box pin 15 to pump relay pin 5 (harness side).
^ Should be 0.2 ohms or less. If not, repair open or high resistance in circuit 854.
9. Reconnect PMV connector C2, measure resistance from pin out box pin 31 to 49.
^ Should be 10-40 ohms. If not, repair open or high resistance in circuit 1292 or 1293.
10. Measure resistance from pin out box pin 31 to 1, and 49 to 1. There should not be any continuity. If you have continuity, repair short to ground on circuit 1292 or 1293.
11. If all check good, replace ABS pump relay, P/N 25553347.
Parts are currently available from GMSPO.