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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Mazda B4000, 2003 Mazda B3000, and 2003 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
  1. If QUICK TEST was not performed, go to QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed, go to next step.
    2. NOTE: If this DTC was set by an intermittent condition, maximum benefit will be obtained by having another technician wiggle harness and connectors when making measurements.
  2. P0403: Check Connection Of EEGR To Harness -  Check EEGR 6-pin harness connector. If connector is properly seated, go to next step. If connector is not properly seated, firmly seat connector. After repair, go to step  11 .
  3. Check For B+ At Harness Connector To EEGR Motor -  With KOEO, disconnect EEGR 6-pin harness connector. Measure voltage between VPWR circuit (Light Blue/Orange wire) at EEGR 6-pin harness connector terminals No. 2 and 6 and negative battery terminal. See Fig 1 . If voltage reading is more than 10.5 volts, go to next step. If voltage reading is 10.5 volts or less, repair open supply circuit (light Blue/Orange wire). See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  11 .
    Fig 1: Identifying EEGR 6-Pin Harness Connector
    G00155543Courtesy of MAZDA MOTORS CORP.
  4. Check EEGR Harness Circuit For Shorts To Ground -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure . Measure resistance between the following breakout box terminals and battery ground:
    • No. 73 (EGRM1 circuit)
    • No. 99 (EGRM2 circuit)
    • No. 72 (EGRM3 circuit)
    • No. 98 (EGRM4 circuit)
    If each resistance reading is more than 10,000 ohms, go to next step. If any resistance reading is 10,000 ohms or less, repair short to ground in wiring harness. After repair, go to step  11 .
  5. Check For Open Circuits In EEGR Harness -  Measure resistance of each EEGR circuit between the following:
    • Breakout box terminal No. 73 (EGRM1 circuit) and EEGR 6-pin harness connector (Violet/Orange wire).
    • Breakout box terminal No. 99 (EGRM2 circuit) and EEGR 6-pin harness connector (Orange/Green wire).
    • Breakout box terminal No. 72 (EGRM3 circuit) and EEGR 6-pin harness connector (Gray/Red wire).
    • Breakout box terminal No. 98 (EGRM4 circuit) and EEGR 6-pin harness connector (Tan/Red wire).
    If each resistance reading is more than 10,000 ohms, go to next step. If any resistance reading is 10,000 ohms or less, repair short to ground in wiring harness. After repair, go to step  11 .
  6. Check EEGR Harness Circuits For Shorts To Each Other -  Measure resistance of each EEGR circuit between breakout box terminal No. 72 and terminals No. 73, 98 and 99. Record readings. Measure resistance of each EEGR circuit between breakout box terminal No. 73 and terminals No. 98 and 99. Record readings. Measure resistance between EEGR circuits by measuring between breakout box terminals No. 98 and 99. Record reading. If each resistance reading is more than 10,000 ohms, go to next step. If any resistance reading is 10,000 or less, repair short in wiring harness. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  11 .
  7. Check For Shorts To Power In EEGR Harness -  Remove breakout box. Reconnect PCM 104-pin harness connector. With KOEO, measure voltage between each EEGR circuit at EEGR 6-pin harness connector and negative battery terminal. See Fig 1 . If voltage reading is less than 0.1 volt, go to next step. If voltage reading is 0.1 volt or more, repair short to power in wiring harness. After repair, go to step  11 .
  8. Check EEGR Motor Windings For Open & Short Circuits -  Turn ignition off. Disconnect PCM 104-pin harness connector. Reconnect EEGR 6-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure . Measure resistance between breakout box terminals No. 71 and/or 97, and the following breakout box terminals:
    • No. 73 (EGRM1 circuit)
    • No. 99 (EGRM2 circuit)
    • No. 72 (EGRM3 circuit)
    • No. 98 (EGRM4 circuit)
    If each resistance reading is 20-24 ohms, go to next step. If any resistance reading is not 20-24 ohms, replace faulty EEGR assembly. After repair, go to step  11 .
  9. Check EEGR Motor Windings For Shorts To Ground -  Turn ignition off. Measure resistance between the following breakout box terminals and negative battery terminal:
    • No. 73 (EGRM1 circuit)
    • No. 99 (EGRM2 circuit)
    • No. 72 (EGRM3 circuit)
    • No. 98 (EGRM4 circuit)
    If each resistance reading is more than 10,000 ohms, replace faulty PCM. After repair, go to step  11 . If any resistance reading is 10,000 ohms or less, replace faulty EEGR assembly. After repair, go to step  11 .
    10. NOTE: If DTCs P0102, P0103, P0107, P0108, P1100 or P1101 is also set, repair these DTCs before continuing with this test procedure.
    NOTE: During next test step, engine speed must be held constant. Performing next test step may generate additional DTCs. After performing next test step, clear any DTCs which may have set.
  10. DTC P0400/P1408: Check For Stuck EGR Valve Operation -  Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector and PCM. See Figure . With KOER, select DIAGNOSTIC DATA LINK. Select PCM. Select ACTIVE COMMAND MODES. Select OUTPUT TEST MODE - BENCH TEST. Using scan tool, access EEGR PID (EGRMC) and MAP PID (MAP) (if available). Operate engine at normal operating temperature with engine speed at 1000-1200 RPM (to prevent stalling). Add a small amount of EGR (about 8-12 steps) by pressing trigger (with EGRMC high-lighted) and using rotary dial while monitoring MAP PID or voltage at breakout box terminal No. 63 (MAP circuit). MAP value should increase as EGR is introduced. If an increase in MAP value is observed, condition is not present at this time. Make sure MAP is properly seated and vacuum source is not blocked. Go to next step. If no increase in MAP value is observed, replace faulty EEGR assembly. After repair, go to next step.
  11. Verify Trouble Shooting Of DTCs Completed -  Reconnect all electrical connectors. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any DTC is present, replace PCM. Repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTCs are set, trouble shooting is complete.
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