Four Needle Sweeps

NOTE: This test requires the use of a "socket box" type testing adapter.

1. With the engine off, and the ignition on measure the voltage between sockets 3 (-) and 12 (+) of the test adapter. If the reading equals approximately 5 volts, proceed with step 2. If the reading does not equal approximately 5 volts, replace the EDS control unit.
2. Measure the voltage between socket box sockets 3 (-) and 17 (+) of the test adapter. Compare the voltages with the table below:

Altitude above sea level Barometric pressure Volts

0 1013 4 ±1
1000 899 3 ±1
2000 795 2 ±1

3. If the values match, then the test is over. If the values do not match, ensure the ignition is off and measure the resistance between the following points: Socket 17 of the test adapter and socket 1 of the altitude correction capsule plug; socket 12 of test adapter and socket 2 of altitude correction capsule plug and socket 3 of test adapter and socket 3 of altitude correction capsule plug. All resistances should be less than 1 Ohm. If the values match, then the test is over. If the values do not match, then check for and repair any open circuit. If no open circuit is found, replace the altitude correction capsule.