DVOM Compatibility Check

CAUTION: A 12 volt (Incandescent) Test Lamp should not be used to test CID, PIP IDM or SPOUT circuit signals. It will load the circuit and may cause erroneous measurements or improper ICM/PCM operation (i.e. Engine stall).

NOTES:

^ When using a DVOM, correct test lead polarity must be followed. The red lead is positive (+) and the black lead is negative (-).

^ To check PIP or CID the engine is "bumped" one revolution of the crankshaft with the starter while watching the voltmeter (do not start engine). Both the CID and PIP signals are digital and should switch between "High" (greater than 8 volts DC) and "Low" (less than 2 volts DC) as the engine turns. To see the signal change using the DVOM the engine must be turned In very short bursts.


EQUIPMENT NOTE: Most DVOM's used by auto technicians belong to a class or type known as "averaging." Examples are the Rotunda Digital Volt-Ohmmeter 007-00001, Fluke 70, 20 series and Fluke 88. Recently technicians have started to use DVOM'S of a different class (True RMS, DVOM's, Fluke 87, 8060A, 8062A, etc.). True RMS DVOM's should not be used with the Pinpoint Tests because they may display different voltage readings depending upon if the DVOM is turned on first and then the test leads are connected, or if the leads are connected first and then the DVOM is turned on. Also they may not auto range to the same range every time and some display significantly different values depending on the range selected. It would be impossible to list all of the meters and how to use each, so we are requesting that you perform the following test to verify your DVOM is compatible with the Pinpoint Tests.

Test Procedure

NOTE: The battery should be charged and the engine must be idling between 700 and 900 rpm.

1. Using a known good EI vehicle, install the EI (Low Data Rate) EI (High Data Rate) diagnostic harness.
2. Connect the EEC Breakout Box to the EI diagnostic harness.
3. Start the vehicle and measure the AC voltage between J18 (RC1I) and ground. The value should be between 1.0 and 2.0 volts AC (1.5 volts AC is typical).

NOTE: If you have the EI (Low Data Rate) hand held testers they may be used instead of the EI Diagnostic Harness/EEC Breakout Box to gain access to J18 (RC1D) and J31 (PIP PCM).

4. With the engine idling, measure between PIP and ground. This reading should be between 6 and 8 volts AC.

Test Results
If the readings you get agree with our test, your DVOM is OK to use with the Ignition Pinpoint Tests. If not, do not use it, it will lead to false parts replacement and the root cause will be difficult or impossible to find.