STS AWD V8-4.6L VIN A (2006)
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A misrouted harness that is too close to high voltage/high current devices such as secondary ignition components, motors, generator etc-These
components may induce electrical noise on a circuit that could interfere with normal circuit operation.
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Electrical system interference caused by a malfunctioning relay, or a control module driven solenoid or switch-These conditions can cause a sharp
electrical surge. Normally, the condition will occur when the malfunctioning component is operating.
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Improper installation of non-factory or aftermarket add on accessories such as lights, 2-way radios, amplifiers, electric motors, remote starters,
alarm systems, cell phones, etc-These accessories may lead to interference while in use, but do not fail when the accessories are not in use. Refer
to Checking Aftermarket Accessories.
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Test for an open diode across the A/C compressor clutch and for other open diodes. Some relays may contain a clamping diode.
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The generator may be allowing AC noise into the electrical system.
INCORRECT CONTROL MODULE
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There are only a few situations where reprogramming a control module is appropriate:
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A new service control module is installed.
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A control module from another vehicle is installed.
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Revised software/calibration files have been released for this vehicle.
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Verify that the control module contains the correct software/calibration. If incorrect programming is found, reprogram the control module with the
most current software/calibration. Refer to Control Module References for replacement, setup, and programming.
IMPORTANT: DO NOT re-program the control module with the SAME software/calibration files that are already present in the control module.
This is not an effective repair for any type of concern.
Testing for Short to Ground
TESTING FOR SHORT TO GROUND
NOTE: Refer to Test Probe Notice.
The following procedures test for a short to ground in a circuit.
With a DMM
1. Remove the power feed (i.e. fuse, control module) from the suspect circuit.
2. Disconnect the load.
3. Set the rotary dial of the DMM to the ohm position.
4. Connect one lead of the DMM to one end of the circuit to be tested.
5. Connect the other lead of the DMM to a good ground.
6. If the DMM does NOT display infinite resistance (OL), there is a short to ground in the circuit.
With a Test Lamp
1. Remove the power feed (i.e. fuse, control module) from the suspect circuit.
2. Disconnect the load.
3. Connect one lead of the test lamp to battery positive voltage.
4. Connect the other lead of the test lamp to one end of the circuit to be tested.
5. If the test lamp illuminates, there is a short to ground in the circuit.
Fuse Powering Several Loads
1. Review the system schematic and locate the fuse that is open.
2. Open the first connector or switch leading from the fuse to each load.
3. Connect a DMM across the fuse terminals (be sure that the fuse is powered).
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When the DMM displays voltage the short is in the wiring leading to the first connector or switch.
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If the DMM does not display voltage
4. Close each connector or switch until the DMM displays voltage in order to find which circuit is shorted.
Troubleshooting with a Digital Multimeter
TROUBLESHOOTING WITH A DIGITAL MULTIMETER
NOTE: Refer to Test Probe Notice.
IMPORTANT: Circuits which include any solid state control modules, such as the powertrain control module (PCM), should only be tested with a 10
megohm or higher impedance digital multimeter such as the J 39200 Digital Multimeter (DMM).
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
future reference.
A DMM should be used instead of a test lamp in order to test for voltage in high impedance circuits. While a test lamp shows whether voltage is present,
a DMM indicates how much voltage is present.
