P258A Electric Vacuum Pump Circuit
August 27, 2017
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P258A Code - with the ignition on, battery voltage above 10.0 volts. Set conditions, the PCM detects an open or short circuit fault on the vacuum pump relay control circuit. Default actions, this is a non MIL fault.
Possible causes:
Step 2. Check the fused ignition runs/start circuit
Turn the ignition off. Remove the EVP relay from the relay connector. Turn the ignition on, using a 12-volt test light connected to ground, probe the fused igntion RUN/START circuit (terminal 85) at the EVP relay connector.
Does the test light illuminate brightly?
Yes, go to step 3.
No, repair the fused ignition RUN/START circuit for an open.
Step 3. EVP relay
Turn the ignition off, measure the resistance of the EVP relay coil. Measure across terminals 85 and 86 of the relay.
Is the resistance between 60.0 and 80.0 Ohms?
Yes, go to step 4.
No, replace the EVP relay.
Step 4. Check the EVP relay control circuit for an open/high resistance
Disconnect the PCM harness connector. Measure the resistance of the Vacuum Pump Relay control circuit between the EVP relay connector and the PCM harness connector.
Is the resistance below 3.0 Ohms?
Yes, go to step 5.
No, repair the Vacuum Pump control circuit for an open or high resistance.
Step 5. Check the EVP relay control circuit for a short to ground
Check for continuity between ground and the Vacuum Pump relay control circuit at the EVP relay socket.
Is there between ground and the Vacuum Pump relay control circuit?
Yes, repair the EVP relay control circuit for a short to ground.
No, go to step 6.
Step 6. Check related PCM and component connections
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| wiring diagram |
Possible causes:
- Fused run/start circuit open.
- Vacuum pump relay control circuit open/high resistance.
- Vacuum pump relay control circuit shorted to ground.
- Electric vacuum pump (EVP) relay.
- Powertrain Control Module (PCM).
Diagnose DTC P258A Electric Vacuum Pump Circuit
Step 1. Check for an active DTC
Turn the ignition on. With the scan tool, read DTC.
Is the DTC active or pending?
Yes, go to step 2.
No, perform the PCM intermittent condition.
No, perform the PCM intermittent condition.
Step 2. Check the fused ignition runs/start circuit
Turn the ignition off. Remove the EVP relay from the relay connector. Turn the ignition on, using a 12-volt test light connected to ground, probe the fused igntion RUN/START circuit (terminal 85) at the EVP relay connector.
Does the test light illuminate brightly?
Yes, go to step 3.
No, repair the fused ignition RUN/START circuit for an open.
Step 3. EVP relay
Turn the ignition off, measure the resistance of the EVP relay coil. Measure across terminals 85 and 86 of the relay.
Is the resistance between 60.0 and 80.0 Ohms?
Yes, go to step 4.
No, replace the EVP relay.
Step 4. Check the EVP relay control circuit for an open/high resistance
Disconnect the PCM harness connector. Measure the resistance of the Vacuum Pump Relay control circuit between the EVP relay connector and the PCM harness connector.
Is the resistance below 3.0 Ohms?
Yes, go to step 5.
No, repair the Vacuum Pump control circuit for an open or high resistance.
Step 5. Check the EVP relay control circuit for a short to ground
Check for continuity between ground and the Vacuum Pump relay control circuit at the EVP relay socket.
Is there between ground and the Vacuum Pump relay control circuit?
Yes, repair the EVP relay control circuit for a short to ground.
No, go to step 6.
Step 6. Check related PCM and component connections
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