Diagnosis And Testing-Horn Relay: Notes

The horn relay (Fig 1 ) is located in the Junction Block (JB) on the left end of the instrument panel in the passenger compartment of the vehicle. If a problem is encountered with a continuously sounding horn, it can usually be quickly resolved by removing the horn relay from the JB until further diagnosis is completed. See the fuse and relay layout label affixed to the inside surface of the fuse access panel for horn relay identification and location. For complete circuit diagrams, refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

Fig 1: Identifying Horn Relay

Courtesy of DAIMLERCHRYSLER CORP.

1. Remove the horn relay from the JB. (Refer to REMOVAL  ) for the procedures.
2. A relay in the de-energized position should have continuity between terminals 87A and 30, and no continuity between terminals 87 and 30. If OK, go to Step 3. If not OK, replace the faulty relay.
3. Resistance between terminals 85 and 86 (electromagnet) should be 75 +/- 5 ohms. If OK, go to Step 4. If not OK, replace the faulty relay.
4. Connect a battery to terminals 85 and 86. There should now be continuity between terminals 30 and 87, and no continuity between terminals 87A and 30. If OK, perform the Relay Circuit Test that follows. If not OK, replace the faulty relay.