Saw your post on TechSHO earlier and posted this response. Copied it here to be sure you get it:
Brandyn,
First of all, you will need a meter instead of the test lamp to test the
inputs to the ICR. When you placed the test lamp across pins 11 & 18, you
placed a low impedence across an input that energizes the corresponding
relay within the module. Please note, these particular relays always have
Vbatt (ignition in RUN or START) on one side of the coil and are energized
when the PCM grounds the other side via a power switching transistor (or
equivilent).
For the following, I am referring to schematics from Mitchell's for the 92
SHO. I don't have the Helms EVTM, so there may be errors. If someone who
does have the EVTM can crosscheck and verify or correct info....
The output of the IRC (aka CCRM, IRCM, etc depending on year) for the fuel
pump is on pin 5 (PINK/BLACK). My schematic shows that the switched output
of both the LOW and HIGH FP relays is connected to pin 5 internally. The
supply to the other relay switch contacts is as follows: LOW - pin 10 and
HIGH - pin 12 (both BLACK/ORANGE). The high side of each coil is connected
to the Vbatt bus internally and is supplied to the IRC internally from the
EEC Power relay.
Troubleshoot as follows with the ignition switch to RUN: Note (Vbatt refers
to the battery supply voltage). All voltages are measure with respect to
ground unless otherwise noted. Same results should be obtained with
ignition switch in START.
1) IRC pin 8 (YEL). If Vbatt, go to #2, otherwise troubleshoot fusible
link in engine compartment fuse block.
2) IRC pin 24 (RED). If Vbatt, go to #3, otherwise go to 2a.
a) Troubleshoot ignition coil fuse(#12 engine compartment FB) or
ignition switch circuit.
3) Measure pins 11 and 18. Both should measure Vbatt Open circuit voltage
through relay coils. If either (or both) measures significantly less than
Vbatt, replace the IRC. If both measure Vbatt, go to step 4.
4) Open inertia switch in trunk compartment by sharply slapping it. Connect
meter to IRC pin 5. One at a time, ground pins 11 and 18 to an available
ground point. When each pin is grounded, you should hear a relay click
inside the IRC and you should read Vbatt on pin 5. If either fails, the IRC
is defective.
5) Reset the inertia switch. Repeat the tests in #4. The results should
be the same except the fuel pump should energize also.
Note: The inclusion in the service documentation of the "LOW" FP circuit
implies that there is a dropping resistor somewhere that is in circuit when
the LOW FP relay is energized. Unfortunately, it is not documented in any
of the schematics that I have consulted....They all indicate that the LOW
and HIGH relays are simply in parallel, which doesn't make any sense. I
have seen references that it is the large wirewound resistor mounted at the
top center of the firewall (engine side). If this is the case and there is
a resistor inline with the LOW side circuit, the output of the complete
circuit as supplied to the inertia switch would be somewhat lower than Vbatt
during the loaded LOW relay test above. My guess would be anywhere from 6
Vdc up almost Vbatt.
Hope this helps.
To all, please comment or send corrections. Please note that this covers
only the schematics for the 92.
Steve
