Fuel Pump Relay: Testing and Inspection

Relay testing is necessary only if the fuel pump does not run when the engine is cranking or running. Perform tests in the order listed.

Fuel Pump Relay (Circuit Open Relay):

QUICK TEST

1. Remove steering column cover and, using a jumper wire, apply 12 volts to the back off terminal "STA" and terminal "B" of the relay harness connector, with the ignition "OFF" and relay connected.

^ Fuel pump should operate.

2. Remove jumper wire, turn ignition "ON" and ground the back of terminal "Fc" of the relay harness connector, with the relay connected.

^ Fuel pump should operate.

If pump operates as described in steps #1 and #2 of this test, relay is OK.

If pump does not operate in BOTH steps #1 and #2 of the quick test, continue testing.

TEST 1 - RELAY SWITCHING FUNCTION CHECK

Relay And Resistance Check:

1. Disconnect relay from its harness connector.

2. Apply 12 volts and ground to the relay terminals listed below and check for the correct result.

12V/Grnd - CORRECT RESULT
"STA"/"E1" - Energizes relay, connects terminals "B" and "Fp" (continuity).
"B"/"Fc" - Energizes relay, 12 volts becomes available at terminal Fp.

If results are not correct as described, replace relay.

TEST 2 - RELAY RESISTANCE CHECK

Check resistance between the following relay terminals.

"STA"/"E1" - Resistance...21 - 43 ohms
"B"/"Fc" - Resistance...109 - 226 ohms
"B"/"Fp" - Resistance...infinite (no continuity)

If results are not correct as described, replace relay.

TEST 3 - RELAY CIRCUIT (WIRING) CHECK

Check voltage at the following terminals with the relay installed, under the conditions listed below.

3A - IGNITION "OFF"
No voltage at any terminal.

3B - IGNITION "ON" ENGINE NOT RUNNING

Terminal "STA" - 0 volts
Terminal "B" - 12 volts
Terminal "Fp" - 0 volts
Terminal "Fc" - 12 volts


3C - IGNITION IN "START" POSITION (CRANKING)

Terminal "STA" - 12 volts
Terminal "B" - 12 volts
Terminal "Fp" - 12 volts
Terminal "Fc" - 0 volts (or nearly zero)

3D - IGNITION "ON" ENGINE RUNNING

Terminal "STA" - 0 volts
Terminal "B" - 12 volts
Terminal "Fp" - 12 volts
Terminal "Fc" - 0 volts (or nearly zero)

NOTE: Relay terminal "E1" is a ground.

If voltage at any terminal is not correct, check the wiring associated with that terminal.

If 12 volts is present at terminal "Fc" during engine cranking or engine running, and the engine dies after starting, check for open in wiring between that terminal and the engine control unit. If wiring is OK, check ECU connectors for good connections and check ECU grounds. If no wiring problems are found, faulty ECU fuel pump relay ground circuit is indicated.