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1. Disconnect the battery negative cable 2. Install the male end of the J 38758 to the negative battery terminal. 3. Turn OFF the test switch. 4. Install the negative battery cable to the female end of the test switch. 5. Install the Scan Tool (or equivalent) or wait for 20 minutes. 6. Turn ON the test switch. 7. Road test the vehicle while activating all accessories, including the radio and the air conditioning. 8. Lower the door glass, then exit the vehicle. Do not move the door handle after closing the door. 9. Open the hood. Important The power down timer will reset to 20 minutes if any wake up inputs are received by a Class 2 device (after the scan tool has put all Class 2 devices to sleep). 10. Put all of the Class 2 devices into the sleep mode. 11. Turn OFF the ignition switch. Remove the key. Important From this point on, electrical continuity must be maintained in the ground circuit of the battery through the Test Switch J 38758 in the ON position or through the ammeter J 39200 . 12. Components such as PCM, VCM, Automatic Air Conditioning, and the Truck Body Control Module have timers that draw several amps of current while they cycle down. This can give a false parasitic drain reading. Wait 20 minutes for these components to power down before continuing this test (or use the scan tool to put all Class 2 devices to sleep). 13. Connect a jumper wire with a 10 A fuse J 36169-A to the terminals of the test switch. 14. Turn the test switch to the OFF position. 15. Wait ten seconds. If the fuse does not blow, the current is less than 10 A. The ammeter can be used safely. 16. Before the fused jumper wire is removed, turn the test switch to the ON position. Important If an ammeter other than the J 39200 is used, ensure that the vehicle does not have a high current drain that would damage the ammeter when connected to the circuit. 17. Perform the following procedure in order to detect a high current drain: A. Set the ammeter J 39200 to the 10 A scale. B. Connect the ammeter to the test switch terminals. C. Turn OFF the test switch. This allows the current to flow through the ammeter. D. Wait one minute, then inspect the current reading. Ñ When there is a current reading of 2 A or less, turn ON the test switch, this maintains continuity in the electrical system. Ñ Then, switch the meter down to the 2 A scale, for a more accurate reading, when the test switch is reopened. E. Open the test switch. F. Take the reading in milliamps. G. Note the battery reserve capacity. Refer to Battery Usage . Ñ Divide this number by 4. Example: 90/4 = 22.5 Ñ Compare this to the ammeter reading. Ñ The current drain in milliamps should not exceed this number. Ñ Example: if a battery has a reserve capacity of 90 minutes, the current drain should not exceed 22 milliamps. H. When the current draw is too high, remove the electrical system fuses one at a time until the draw returns to a value less than or equal to specifications. Ñ Start with the fuses that are hot all the time. Ñ To remove the fuse, you must first open the door, which causes a high enough current flow to damage the ammeter. Ñ Protect the ammeter, without disturbing the electrical continuity, by turning ON the test tool before opening the door. Ñ Remove the courtesy lamp fuse. Ñ Note the ammeter reading. Ñ If the parasitic load is still excessive, start removing the remaining fuses one at a time. Ñ Keep the courtesy lamp fuse out during diagnosis, so the door can remain open. Ñ Perform Steps 11 through 13 each time a fuse is removed. I. Removing the PCM or VCM fuse should cause a drop of less than 10 milliamps. A drop greater than 10 milliamps indicates a possible short to ground. J. Check the orange wires along with the components connected to the orange wires. No drop in the milliampere reading indicates the PCM or VCM is not drawing current. K. Repeat the parasitic current drain test procedure after any repair has been completed. L. When the cause of the excessive current draw has been located and repaired, remove the ammeter and the parasitic draw test switch.
