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Home >> Mazda >> 1999 >> B2500 TL, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Engine Controls - Self-Diagnostics - EEC-V - 6.8L (99S E Series & 99S F350 To F550)) >> System Tests >> Test Th: Reverse Switch >> Diagnostic Aids

Diagnostic Aids

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Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following.

  1. 1) DTC P0812: Check RS Switch Function

    Ensure gearshift lever is in "N" position during KOEO self-test. Turn ignition switch to ON position. Using scan tool, access RS PID. Move gear shift lever in and out of "N" position. If scan tool reading changes from ON to OFF, problem is intermittent. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. If connector and terminals are okay, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION (VID) BLOCK PROCEDURE . If scan tool reading does not change from ON to OFF, go to next step.

  2. 2) Check RS Switch

    RS switch is located near shift linkage. Inspect switch and bracket for damage. Repair as necessary. Disconnect RS switch connector. Measure resistance between RS switch terminals with shift lever in "R" position. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace RS switch.

  3. 3) Check For Open Circuit

    Turn ignition switch to OFF position. Disconnect scan tool from DLC. Measure resistance of RS circuit between PCM connector terminal B10 and RS switch connector RS terminal. Measure resistance of SIG RTN circuit between PCM connector terminal B17 and RS switch connector SIG RTN terminal. If both resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, repair appropriate open circuit.

  4. 4) Check RS Circuit For Short To Ground Or Wires Shorted Together

    Measure resistance between PCM connector terminals No. B10 (RS) and B17 (SIG RTN). Measure resistance between PCM connector terminal B10 (RS) and ground. If both resistance readings are more than 10 k/ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION (VID) BLOCK PROCEDURE . If any resistance reading is 10 k/ohms or less, repair short to ground or wires shorted together.
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