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Home >> Geo >> 1997 >> Prizm Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing 1.6 & 1.8L >> Circuit Tests >> Test A1-7A - Fuel System Diagnosis Circuit Opening Relay Check >> Diagnostic Aids

Diagnostic Aids

A restricted or leaking fuel feed line or hose will cause an engine no start condition. Check fuel sender assembly connection inside fuel tank for poor connections. See TEST A1-7B  under CIRCUIT TESTS for fuel pressure test.

An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for an open or loose or disconnected terminals.

If engine starts while cranking and then stalls when ignition switch is in run position, problem may be in circuit opening relay control circuit or PCM may not be providing adequate ground.

  1. Turn ignition on. Using a fused jumper wire, momentarily backprobe PCM 22-pin connector terminal No. 14 (Green/Red wire) to ground. If fuel pump does not run, go to step 3). If fuel pump runs, go to next step.
  2. Using a test light connected to battery voltage, backprobe PCM 22-pin connector terminal No. 14 (Green/Red wire). Crank engine and observe test light. If test light illuminates, go to TEST A1-7B  under CIRCUIT TESTS. If test light does not illuminate, replace PCM. If repair was necessary, go to step 13).
  3. Disconnect circuit opening relay (located on driver's side, behind kick panel). Using a voltmeter, measure voltage between circuit opening relay connector terminal No. 3 (Black wire) and ground. Crank engine. If reading is 10 volts or more, go to next step. If reading is less than 10 volts, repair open in Black wire between Park/Neutral Position (PNP) switch (A/T) or Clutch Pedal Position (CPP) switch (M/T) and circuit opening relay. If repair was necessary, go to step 13).
  4. Using a test light connected to battery voltage, probe circuit opening relay connector terminal No. 5 (White/Black wire). Crank engine. If test light illuminates, go to next step. If test light does not illuminate, repair open circuit opening relay ground circuit (White/Black wire). If repair was necessary, go to step 13).
  5. Connect a fused jumper wire between battery voltage and circuit opening relay connector terminal No. 1 (Blue/Black wire). If fuel pump runs, go to next step. If fuel pump does not run, go to step 10).
  6. Disconnect jumper wire. Turn ignition on. Using a test light connected to ground, probe circuit opening relay connector terminal No. 2 (Black/Red wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  7. Turn ignition off. Using a test light connected to battery voltage, probe circuit opening relay connector terminal No. 4 (Green/Red wire). Crank engine and observe test light. If test light illuminates, replace circuit opening relay. If repair was necessary, go to step 13). If test light does not illuminate, go to step 9).
  8. Check for open or short in Black/Red wire between circuit opening relay connector terminal No. 2 and EFI F-HTR relay (located in engine compartment relay/fuse box). Repair as necessary. If repair was necessary, go to step 13).
  9. Check for open or short in Green/Red wire between circuit opening relay and PCM. Repair as necessary. If Green/Red wire was okay, replace PCM. If repair was necessary, go to step 13).
  10. With jumper wire still connected to circuit opening relay connector terminal No. 1, disconnect fuel sender unit connector. Using a test light connected to ground, probe fuel sender harness connector terminal No. 4 (Blue/Black wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 12).
  11. Disconnect jumper wire. Using a test light connected to battery voltage, probe fuel sender harness connector terminal No. 5 (White/Black wire). If test light illuminates, replace fuel pump. If test light does not illuminate, repair open fuel pump ground (White/Black wire). If repair was necessary, go to step 13).
  12. Check for an open or short in fuel pump power feed (Blue/Black wire) between fuel pump and circuit opening relay. Repair as necessary. Go to next step.
  13. Using scan tool, clear Diagnostic Trouble Codes (DTCs). Attempt to start engine. If engine starts and runs, allow engine to idle until normal operating temperature is reached. Using scan tool, check for DTCs. If any DTCs reset, go to appropriate CIRCUIT TEST in the TESTS W/CODES article. If no DTCs reset, system is okay. If engine does not start, return to step 1).
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