
SECTION 5: TROUBLESHOOTING GUIDE
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EPI800 Manual.doc
EPI 800 MANUAL
2001 Vision Microsystems Inc.
Follow these steps to troubleshoot the problem.
Step 1. Determine which probes are suspect.
a. Turn power ON to the engine instruments. Scan all CHT and
EGT positions for blank graphs. If all positions are blank
there is most likely a DPU fault and the troubleshooting
process can be stopped and the factory contacted. If not, the
probe circuit(s) may be open. Record which probe positions
are blank.
Step 2. Check probe for integrity.
a. Shut OFF power to instrument system.
b. Using a digital ohmmeter equipped with fine point test
leads, carefully measure resistance between the
suspected probes metal terminals. This value should
be between 4 to 10 ohms. If not, the probe should be
replaced.
c. Check the probe for electrical leakage. Disconnect the
probe from the harness. Connect meter between each
probe lead and the probes metal body. The resistance
should be greater than 1 meg-ohm. If it is OK, then
reconnect the leads to the harness. If not, the probe
should be replaced.
Step 3. Check wire harness integrity
a. Remove the P2 connector from DPU and check for
continuity between the respective harness lug terminal
and P2 pin. Resistance should be less than 8 ohms. If
not, inspect all connectors and pins for connectivity to
the harness wires and correct them.
b. Also check that the correct pin locations were used
(with regard to the suspect probe) in P2 when the
harness was built.