Centrifugal Advance Mechanism-Check And Replacement; Ignition Pick-Up Coil (V6 Engines Only)-Check And Replacement; Distributor Details (V6 Engines) - Jeep cherokee 1989 Owner's Manual

12.3 Before removing the pick-up coil, unplug the lead from the
ignition module
Replacement
7 Detach the cable from the negative battery terminal.
Remove the distributor cap and rotor (see Chapter 1).
8
The following procedure is easier if you remove the distributor (see
9
Section 13), but it's not absolutely necessary that you do so.
10 If you do decide to remove the distributor, place it in a bench vise.
11 Remove the pickup coil (see Section 9).
12 Remove the vacuum hose and attaching screws from the vacuum
advance mechanism (see illustration 9.5). Tilt the vacuum advance
mechanism to disengage the link from the pickup coil pin, which pro-
trudes through the distributor housing. If necessary, loosen the base
plate screws to get more clearance. Lift the vacuum advance mecha-
nism out of the distributor housing.
13 To calibrate a new vacuum advance mechanism:
a) Insert an appropriately sized Allen wrench into the vacuum hose
tube of the old vacuum advance mechanism; count the number
of clockwise turns necessary to bottom the adjusting screw.
b) Turn the adjusting screw of the replacement vacuum advance
mechanism clockwise to bottom it, then turn it counterclockwise
the same number of turns you counted above.
14 lnstall the advance mechanism on the distributor housing. Make
sure the link is engaged on the pin of the pickup coil.
15 lnstall and tighten the vacuum advance mechanism attaching
screws. If you loosened the base plate screws, tighten them too.
16 lnstall the pickup coil (see Section 9).
17 lnstall the distributor (see Section 13).
18 lnstall the distributor cap and rotor (see Chapter 1).
19 Attach the cable to the negative battery terminal.
20 Check the ignition timing and adjust it, if necessary (see Chap-
ter 1).
21 Attach the vacuum hose to the vacuum advance mechanism.
11 Centrifugal advance mechanism
(1984 and 1985 four-cylinder models only)
1 Detach the vacuum hose from the vacuum advance mechanism
and plug it (see illustration 9.5).
2
Hook up a timing light and tachometer in accordance with the
manufacturer's instructions.
3 Start the engine and, with the engine idling, watch the timing
marks at the front of the engine with the timing light (see Chapter 1 for
more information).
4 Slowly increase engine speed t o 2000 rpm. Timing should ad-
vance smoothly as engine speed increases. If it advances unevenly,
the centrifugal advance mechanism is faulty. Replace the distributor
(see Section 12). You will need to switch the following parts to the re-
placement distributor:
a) Cap and rotor (see Chapter 1).
b) Trigger wheel and/or pickup coil assembly (see Section 9).
c) Vacuum advance mechanism (see Section 10).
The Motor Manual Guy
Chapter 5 Engine electrical systems
-
check and replacement
12.4 Ohmmeter connections for checking the pick-up coil on a
typical V6
12 Ignition pick-up coil (V6 engines only)
replacement
Refertoillustrations 12.3, 12.4, 12.9, 12.7la, 12.11b, 12.11c, 12.14a
and 72.14b
Check
1 Detach the cable from the negative terminal of the battery.
2 Remove the distributor cap and rotor (see Chapter 1).
Detach the pick-up coil leads from the module (see illustration).
3
4 Connect one lead of an ohmmeter to the terminal of the pick-up
coil lead and the other to ground as shown (see illustration). Flex the
leads by hand to check for intermittent opens. The ohmmeter should
indicate infinite resistance at all times. If it doesn't, the pick-up coil i
defective and must be replaced.
5 Connect the ohmmeter leads to both terminals of the pick-up coi
Flex the leads by hand to check for intermittent opens. The ohmmeter
should read one steady value between 500 and 1500 ohms as the
leads are flexed by hand. If it doesn't, the pick-up coil is defective and
must be replaced.
Replacement
6 Remove the distributor (see Section 13).
Remove the two rotor mounting screws and remove the rotor.
7
8 Disconnect the pick-up coil leads from the module.
9 On models with a Hall-effect switch, remove the switch retaining
screws and the switch (see illustration).
PICKUP COIL
ASSEMBLY
MODULE
" P "
TERMINAL

12.9 Distributor details (V6 engines)

5-5
-
check and
L L EFFECT SWITCH
IGNITION COIL
CONNECTOR
TERMINALS
LATCH
CONNECTOR
CKUP COIL LEADS
DISCONNECTED
FROM MODULE