GMC T Series 1994 Repair Manual page 616

10. Pickup coil (11).
11. Two screws (25) holding the module to the hous­
ing.
12. Module (14).
I?
Inspect
1. Cap for cracks or tiny holes. Replace the cap if it is
worn, or damaged.
2. Metal terminals in the cap for corrosion. Scrape
them clean with a knife or replace the cap.
3. Rotor for wear or burning at the outer terminal. The
presence of carbon on the terminal indicates rotor
wear and the need for replacement.
4. Shaft for shaft-to-bushing looseness. Insert the
shaft in the housing. If the shaft wobbles, replace
the housing and/or shaft.
5. Housing for cracks or damage.
Measure
Tools Required:
J 24642-F Module Tester
1. Resistance of the pickup coil with an ohmmeter.
A. Connect an ohmmeter to either pickup coil lead
and the housing as shown in figure 5, step 1.
INSPECTION AND
ELECTRICAL TESTS
The reading should be infinite. If not, replace
the coil.
B. Connect an ohmmeter to both pickup coil leads
as shown in figure 5, step 2. Flex the leads by
hand at the coil and the connector to locate any
intermittent opens. The ohmmeter should read
a constant value in the 500 to 1500 ohm/range.
If not, replace the coil.
2. Electrical performance of the module. The module
can only be checked with an approved module tes­
ter, such as J 24642-F. Follow the directions exact­
ly that come with the tester.
3. Resistance of the ignition coil with an ohmmeter.
A. Connect the ohmmeter as shown in figure 6,
step 1. Use the high scale. The reading should
be infinite. If not, replace the coil.
B. Connect the ohmmeter as shown in step 2. Use
the low scale. The reading should be very low
or zero. If not, replace the coil.
C. Connect the ohmmeter as shown in step 3. Use
the high scale. The meter should not read infi­
nite. If it does, replace the coil.
A
A. Scrape clean metal ground.
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