GMC chervolet camaro 1999 Service Manual page 613

5-138 Antilock Brake System Brakes
DTC C0040 RF Wheel Speed Circuit Malfunction
RF Wheel
Speed
Sensor
0.8 LT BLU
B
0.5 DKGRN
3
4
0.8YEL 833
872
A C130
----------
872
0.5TAN 833
5
C1
(ABS)
5
C1
(ABS!TCS)
----------
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Electronic Brake And Traction
I
High
I Control Module
I
Low
I (EBCM/EBTCM)
I
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I ~
I
Speed Sensor .,,.
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S~nal
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Circuit Description
The speed sensor used on this vehicle is a multiple
pole magnetic pickup. This sensor produces an
AC signal that the EBCM/EBTCM uses the frequency
from to calculate the wheel speed.
Conditions for Setting the DTC
The OTC can be set any time the ignition is in the
RUN position and the EBCM/EBTCM detects an open
or a short to voltage.
Action Taken When the OTC Sets
• A malfunction OTC stores.
• The ABS/TCS disables.
• The amber ABS/TCS indicator(s) turn on.
• The Red BRAKE Warning indicator could turn on.
Conditions for Clearing the OTC
• The condition responsible for setting the OTC no
longer exists and the scan tool Clear OTCs
function is used.
• 100 ignition cycles pass with no OTC(s) detected.
Diagnostic Aids
• It is very important that a thorough inspection of
the wiring and connectors be performed. Failure
to carefully and fully inspect wiring and connectors
may result in misdiagnosis, causing part
replacement with reappearance of the malfunction.
• Thoroughly inspect any circuitry that may be
causing the complaint for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
213274
- Improperly formed or damaged terminals
- Poor terminal-to-wiring connections
- Physical damage to the wiring harness
• The following conditions may cause an intermittent
malfunction:
- A poor connection
- Rubbed-through wire insulation
- A broken wire inside the insulation
• If the customer's comments reflect that the amber
ABS/TCS indicator is on only during moist
environmental conditions (rain, snow, vehicle
wash), inspect all the wheel speed sensor circuitry
for signs of water intrusion. If the OTC is not
current, clear all OTCs and simulate the effects of
water intrusion by using the following procedure:
1. Spray the suspected area with a five
percent saltwater solution.
Add two teaspoons of salt to twelve ounces
of water to make a five percent saltwater
solution.
2. Test drive the vehicle over various road
surfaces (bumps, turns, etc.) above 40 km/h
(25 mph) for at least 30 seconds.
3. If the OTC returns, replace the suspected
harness.
• If an intermittent malfunction exists refer to
Troubleshooting Procedures Cell 4 in Electrical
Diagnosis for further diagnosis.
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