LEMON Manuals: Even more car manuals for everyone
Home >> Mercedes Benz >> 1991 >> 300E Base, 2.6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Fuel Pump Relay (420SEL & 560 Series)

Fuel Pump Relay (420SEL & 560 Series)

  1. Remove fuel pump relay from relay board at left rear of engine compartment. Connect positive lead of voltmeter to relay connector socket No. 8 (relay terminal No. 30) and negative lead to relay connector socket No. 11 (relay terminal No. 31). Measure voltage. If reading is 12 volts, go to step 3). If reading is zero volts, go to next step.
  2. Remove voltmeter negative lead from relay connector socket No. 11 (relay terminal No. 31) and connect lead to vehicle ground. If reading is 12 volts, check for short or open in Brown wire from relay connector socket terminal No. 11 to ground. If voltage is zero, check Red wire from relay connector socket terminal No. 8 for short or open. Repair wiring as required.
  3. Turn on ignition and check voltage at relay connector socket No. 9 (relay terminal No. 15). If reading is zero volts, check Black/Red wire from relay connector socket terminal No. 15 to fuse box for short or open. Repair wiring as required. If reading is 12 volts, go to next step.
  4. Using jumper wire, bridge relay connector socket No. 7 (relay terminal No. 87) and socket No. 8 (relay terminal No. 30). If fuel pump is running, test is completed, replace fuel pump relay. If fuel pump is not running, go to next step.
  5. Check Black/Red/White wire from relay connector socket No. 7 (relay terminal No. 87) to fuel pump for open or short. If wiring is good, replace fuel pump relay. If fuel pump still does not run, replace fuel pump.
scientia non olet · About LEMON Manuals