Fuel Cut-Off DECEL Solenoid (420SEL & 560 Series)
- On California models, program CIS-E control unit to provide on-off ratio output. See TESTING WITH ON-OFF RATIO TESTER in the TESTS W/CODES article in this section. Connect On-Off Ratio Tester (Bosch KDJE-P 600) to diagnostic socket. Start engine and let idle. Ensure engine is at operating temperature. If tester needle is oscillating, go to next step. If tester needle does not oscillate, perform on-off ratio trouble shooting. See TESTING WITH ON-OFF RATIO TESTER in the TESTS W/CODES article in this section.
- Position on-off ratio tester wires to allow tester to reach inside vehicle. Drive vehicle. With engine speed at 2500 RPM, shift transmission selector lever in position "2". When vehicle is decelerating (throttle valve closed), on-off ratio should jump to about 95% when engine RPM drops below 1100 RPM. It will fall momentarily to 50% and the control range is ended. If on-off ratio is as described, test is complete. If on-off ratio is not correct, proceed to next step.
- Check idle speed contacts on throttle valve switch. Check TD signal. Refer to TEST STEP No. 10 for V8 engines in the appropriate TESTS W/CODES article in this section. Test TD signal. Check circuit between CIS-E control unit connector through the idle speed control unit and electronic speedometer for continuity. Resistance should read zero ohms. If resistance is not zero ohms, check for open circuit. If resistance is zero ohms, test is complete.