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Test M - EGR On/Off Control

NOTE: Code 34 may be result of high volume exhaust vent system which reduces backpressure. If this is suspected, perform test in well-ventilated area without exhaust vent connected.
  1. Code 34. Turn ignition off and wait 10 seconds. Disconnect EGR solenoid harness. With DVOM on 200 ohm scale, measure EGR solenoid resistance. If 65-110 ohms, connect EGR solenoid and go to next step. If less than 65 ohms or more than 110 ohms, replace EGR solenoid and repeat Quick Test.
  2. Turn ignition off and wait 10 seconds. Place DVOM on 20 volt scale. Connect negative DVOM lead to self-test output of self-test connector and positive lead to positive terminal of battery. Insert jumper wire between self-test input and signal return circuit (enter Output State Check). Perform Key On-Engine Off Self-Test until end of Continuous Test Code display. DVOM will read 0 volts. Depress and release throttle and observe DVOM reading. If DVOM registered high reading, stay in Output State Check and go to next step. If DVOM did not register high reading, depress throttle to wide open position and release. If output voltage does not go to high reading, go to Test K, step 13). Leave test equipment connected.
  3. Place DVOM on 20 volt scale and leave jumper wire inserted. Connect positive lead to vehicle power circuit on EGR solenoid and negative lead to EGR output circuit on solenoid. While observing DVOM, depress and release throttle several times to cycle EGR output on and off. If EGR cycles on and off, go to step 4). If EGR does not cycle on and off, go to step 6).
  4. Disconnect DVOM and leave jumper wire installed. Disconnect vacuum supply at EGR solenoid and install vacuum pump. Disconnect output hose and install vacuum gauge. Apply 6 in. Hg (minimum). Depress and release throttle several times to cycle EGR output while maintaining vacuum at supply hose. Note vacuum gauge reading. If vacuum cycles on and off, go to next step. If vacuum does not cycle on and off, replace EGR solenoid and repeat Quick Test.
  5. Remove jumper wire, vacuum gauge and vacuum pump. With vacuum lines disconnected at EGR solenoid, start engine. If vacuum is present, EEC system is not cause of problem. Check EGR system. If vacuum is not present, correct vacuum source blockage or leak and repeat Quick Test.
  6. Remove jumper wire and leave EGR solenoid disconnected. With ignition on, place DVOM on 20 volt scale. Connect positive lead to vehicle power circuit of EGR solenoid and negative lead to ground. If less than 10.5 volts, repair open circuit and repeat Quick Test. If 10.5 volts or more, go to next step.
  7. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and leave ECA disconnected. With DVOM on 200 ohm scale, measure continuity of EGR harness from EGR circuit to box pin 35. If less than 5 ohms, go to next step. If 5 ohms or more, repair open circuit and repeat Quick Test.
  8. Turn ignition off and wait 10 seconds. Place DVOM on 200,000 ohm scale. Leave breakout box installed and ECA and EGR solenoid disconnected. Measure resistance from box pin 35 to box pins 37 and 57. If 10,000 ohms or more, go to next step. If less than 10,000 ohms, repair short to power and repeat Quick Test.
  9. Turn ignition off and wait 10 seconds. Leave breakout box installed and ECA and EGR solenoid disconnected. With DVOM on 200,000 ohm scale, measure resistance from box pin 35 to box pins 40, 46 and 60 in turn. If less than 10,000 ohms, repair short to ground and repeat Quick Test. If 10,000 ohms or more, replace ECA and repeat Quick Test.
Fig 1: EGR On-Off Control Circuit
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