Corvette V8-5.7L VIN G (1997)
Vehicle Speed Sensor: Diagnostic Aids
Additional Information
NOTE: Do not touch the electrical connections and pins. Do not allow the pins or connections to contact brake fluid. This will damage the EBCM.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the Digital Multimeter (DMM) to ohms, then
pressing the PEAK MIN MAX button. An audible tone will be heard whenever the DMM detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the DMM as well as kept on hand for
reference during new procedures.
NOTE: Turn off power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the DMM. Do not
use the DMM to measure resistance through a solid state module.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic
theory of electricity and know the meaning of voltage (volts), current (amps) and resistance (ohms). You should understand what happens in a circuit
with an open or a shorted wire. You should be able to read and understand a wiring diagram.
The following four-step troubleshooting procedure is recommended:
Check the Problem
Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have
narrowed down the possible causes.
Read the Electrical Schematic
Study the schematic and read the Circuit Description text to gain an understanding of how the circuit should work. Check circuits that share wiring
with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Detail pages.) Try to operate the
shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Find the fault and repair
Narrow down the possible causes.
Use the Troubleshooting Hints.
Make the necessary measurements or checks as given in the System Diagnosis.
Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK,
the most probable cause is component failure.
Test the Repair
Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair.
Checking Terminal Contact
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to the J 38125-A Terminal Repair Kit or the J
38125-4 Instruction Manual for terminal identification), it is important to check terminal contact between a connector and component, or between
in-line connectors, before replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact.
A poor connection between the male and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself,
exposing the terminals to moisture and dirt.
Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit.
Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or
repeatedly separating and joining the connector halves.
Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit.
Follow the procedure below to check terminal contact.
1. Separate the connector halves. Refer to the J 38125-A Terminal Repair Kit or the J 38125-4 instruction manual.
2. Inspect the connector halves for contamination. Contamination will result in a white or green build- up within the connector body or between
