How to use this manual

This manual is designed to assist the technician unfamiliar with Bosch fuel injection systems in locating faults in the L-Jetronic system, isolating the component involved and testing the component for correct function. You will need a volt-ohmmeter and a pressure gauge as described in the Tool List. Electrical measurements are made at the terminals of the large plug at the end of the wiring harness after it is removed from the control unit, or at the terminals of the individual components themselves. Most components of this system cannot be repaired and will have to be replaced once you have determined them defective.

If you are already familiar with Bosch EFI-systems and can identify and locate all the components in the vehicle, go directly to the Troubleshooting Chart to track down the faulty component according to the engine symptom given. Then go to the Component Test instructions for directions on testing the suspected component. Technicians who are experienced in the various tests on this vehicle model can go directly to the Test Chart where the individual test steps and values are given.

An Electric Wiring Diagram is included in the manual to assist you in tracing cables and locating the various terminals. Be sure to check and if necessary reset the CO adjustment before returning the car to the customer.

Safety instructions

  • Never start the engine without battery cables firmly connected.

  • Never jump the battery to start the car.

  • Never remove cables from battery with engine running.

  • Always remove cables from battery before charging.

  • Never remove or attach wiring harness plug to Control Unit with the ignition on.

  • When turning the engine over to check compression, unplug the red cable from the battery to the relays.

  • Before testing the L-Jetronic system, be sure timing, dwell and spark plugs check out OK and are within specification.