Dodge Omni/Horizon/Rampage 1978-1989 Repair Guide

Testing

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The electronic ignition system is controlled by the Chrysler Corporation Lean Burn system, which is actually an emission control system.

The ignition coil can be tested on a conventional coil tester. The ballast resistor, mounted on the firewall, must be included in all tests. Refer to the beginning of Engine and Engine Overhaul for coil testing.


WARNING
Some of the procedures in this section refer to an adjustable timing light. This is also known as a spark advance tester, i.e., a device that will measure how much spark advance is present going from one point, a base figure, to another. Since precise timing is very important to the Lean Burn System, do not attempt to perform any of the tests calling for an adjustable timing light without one.

CARBURETED ENGINES



Spark Test
  1. Remove the coil wire from the distributor cap and hold it cautiously about 1 / 4 in. (6mm) away from an engine ground, then have someone crank the engine while you check for spark.
  2.  
  3. If you have a good spark, slowly move the coil wire away from the engine and check for arcing at the coil while cranking.
  4.  



Click image to see an enlarged view

Fig. Fig. 1 Remove the coil wire from the distributor cap and hold it cautiously about 1 / 4 in. (6mm) away from an engine ground

  1. If you have good spark and it is not arcing at the coil, check the rest of the parts of the ignition system.
  2.  

No Start
1978-80 MODELS
  1. Measure the battery specific gravity. It must be at least 1.220, temperature corrected. Measure the battery voltage and make a note of it.
  2.  
  3. Disconnect the thin wire from the negative coil terminal.
  4.  
  5. Remove the coil high tension lead at the distributor cap.
  6.  
  7. Turn the ignition ON . While holding the coil high tension lead 1 / 4 in. (6mm) from a ground, connect a jumper wire from the negative coil terminal to a ground. A spark should be obtained from the high tension lead.
  8.  
  9. If there is no spark, use a voltmeter to test for at least 9 volts at the positive coil terminal (ignition ON ). If so, the coil must be replaced. If less than 9 volts is obtained, check the ballast resistor, wiring, and connections. If the car still won't start, proceed to the next step.
  10.  
  11. If there was a spark in Step 4, turn the ignition OFF , reconnect the wire to the negative coil terminal, and disconnect the distributor pick-up coil connection.
  12.  
  13. Turn the ignition ON , and measure voltage between pin B of the pick-up coil connector on the spark control computer side, and a good engine ground. Voltage should be the same as the battery voltage measured in the first step. If it is, go to Step 11. If not, go to the next step.
  14.  



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Fig. Fig. 2 The spark control computer is located in the left front of the vehicle


WARNING
Malfunction of the distributor pick-up coil can be the result of the rotor not properly grounded to the distributor shaft. Remove the rotor and check the metal grounding tab to be sure it is not covered with plastic. If so, replace the rotor with a new one. Clean the top of the distributor shaft and install the rotor, pushing it onto the shaft so the metal tab contacts the shaft. Check for continuity between the interrupter vane and distributor housing. Do not try to start the engine with no continuity.

  1. Turn the ignition OFF and disconnect the terminal connector at the spark control computer.
  2.  


WARNING
Do not remove grease from the 10-wire harness connector.

  1. Check for continuity between pin B of the pick-up coil connector on the computer side, and terminal 3 of the computer connector. If there is no continuity, the wire must be replaced. If continuity exists, go to the next step.
  2.  
  3. With the ignition ON , connect a voltmeter between terminals 2 and 10 of the computer connector. Voltage should be the same as measured in the first step. If so, the computer is defective and must be replaced.
  4.  
  5. Secure the 10 wire computer connector. Turn the ignition ON . Hold the coil high tension lead (disconnected at the distributor cap) about 1 / 4 in. (6mm) from a ground. Connect a jumper wire between pins A and C of the distributor pick-up coil connector. If a spark is obtained, the distributor pick-up is defective and must be replaced. If not, go to the next step.
  6.  



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Fig. Fig. 3 The 10 wire connector is plugged into the spark control computer

  1. Turn the ignition OFF . Disconnect the 10 wire computer connection.
  2.  
  3. Check for continuity between pin C of the distributor connector and terminal 9 of the computer connector. Also check for continuity between pin A of the distributor connector and terminal 5 of the computer connector. If continuity exists, the computer is defective and must be replaced. If not, the wires are damaged. Repair them and recheck, starting at Step 11.
  4.  



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Fig. Fig. 4 Distributor pick-up coil connector 1978-80

1981 AND LATER
  1. Make sure the battery is fully charged, then measure and record the battery voltage.
  2.  
  3. Remove the coil secondary wire from the distributor cap.
  4.  
  5. With the key ON , use the special jumper wire and momentarily connect the negative terminal of the ignition coil to ground while holding the coil secondary wire (using insulated pliers and heavy gloves) about 1 / 4 from a good ground. A spark should fire.
  6.  



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Fig. Fig. 5 Use this special jumper wire, then momentarily connect the negative terminal of the ignition coil to ground while holding the coil secondary wire

  1. If spark was obtained, go to Step 9.
  2.  
  3. If no spark was obtained, turn OFF the ignition and disconnect the 10-wire harness going into the Spark Control Computer. Do not remove the grease from the connection.
  4.  
  5. With the ignition key ON , use the special jumper wire and momentarily connect the negative terminal of the ignition coil to ground while holding the coil wire 1 / 4 in. (6mm) from a good engine ground. A spark should fire.
  6.  
  7. If a spark is present, the computer output is shorted: replace the computer.
  8.  
  9. If no spark is obtained, measure the voltage at the coil positive terminal. It should be within 1 volt of battery voltage. If voltage is present but no spark is available when shorting negative terminal, replace the coil. If no voltage is present, replace the coil or check the primary wiring.
  10.  
  11. If voltage was obtained but the engine will not start, hold the carburetor switch open with a thin cardboard insulator and measure the voltage at the switch. It should be at least 5 volts. If voltage is present, go to Step 16.
  12.  
  13. If no voltage is present, turn the ignition switch OFF and disconnect the 10 terminal wire harness going into the computer.
  14.  
  15. Turn the ignition switch ON and measure the voltage at terminal 2 of the harness. It should be within 1 volt of battery voltage.
  16.  
  17. If no battery voltage is present, check for continuity between the battery and terminal 2 of the harness. If no continuity, repair fault and repeat the previous step.
  18.  
  19. If voltage is present turn ignition switch OFF and check for continuity between the carburetor switch and terminal 7 on connector. If no continuity is present, check for open wire between terminal 7 and the carburetor switch.
  20.  
  21. If continuity is present, check continuity between terminal 10 and ground. If continuity is present here, replace the computer. Repeat Step 9.
  22.  
  23. If no continuity is present, check for an open wire. If wiring is OK but the engine still won't start, go to next step.
  24.  
  25. Plug the 10 terminal dual connector back into the computer and turn the ignition switch ON , hold the secondary coil wire near a good ground and disconnect the distributor harness connector. Using a regular jumper wire (not the special one mentioned earlier), jump terminal 2 to terminal 3 of the connector. A spark should fire at the coil wire. Make and break the connection at terminal 2 or 3 several times and check for good spark at the coil wire.
  26.  



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Fig. Fig. 6 Using a regular jumper wire, jump terminal 2 terminal 3 of the connector. A spark should fire at the coil wire

  1. If spark is present at the coil wire but the engine won't start, replace the Hall Effect pick-up and check the rotor for cracks or burning. Replace as necessary.
  2.  


WARNING
When replacing a pick-up, always make sure rotor blades are grounded using an ohmmeter.

  1. If no spark is present at the coil wire, measure the voltage at terminal 1 of the distributor harness connector: it should be within 1 volt of battery voltage.
  2.  
  3. If correct, disconnect the 10 terminal dual connector from the computer and check for continuity between terminal 2 of distributor harness and terminal 9 of the dual connector. Repeat test on terminal 3 of distributor harness and terminal 5 of dual connector. If no continuity, repair the harness. If continuity is present, replace the computer and repeat Step 16.
  4.  



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Fig. Fig. 7 Check for continuity between terminal 2 of distributor harness and terminal 9 of the dual connector. Repeat test on terminal 3 of distributor harness and terminal 5 of dual connector

  1. If no battery voltage is present in Step 18, turn OFF the ignition switch, disconnect the 10 terminal dual connector from the computer and check for continuity between terminal 1 of distributor harness and terminal 3 of dual connector. If no continuity, repair wire and repeat Step 16.
  2.  
  3. If continuity is present, turn the ignition switch ON and check for battery voltage between terminal 2 and terminal 10 of the dual connector. If voltage is present, replace the computer and repeat Step 16. If no battery voltage is present, the computer is not grounded. Check and repair the ground wire and repeat Step 16.
  4.  

Poor Performance

Before proceeding with these tests, be sure the ignition timing and idle speed are as specified.

CARBURETOR SWITCH
  1. With the key OFF , disconnect the 10-wire harness from the Spark Control Computer.
  2.  



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Fig. Fig. 8 Carburetor continuity test is similar on the 1.6L and 1.7L-2.2L shown

  1. With the throttle completely closed, check for continuity between pin 7 of the harness connector and a good ground. If there is no continuity, check the carburetor switch and wire. Recheck the timing.
  2.  
  3. With the throttle open, check for continuity between pin 7 of the harness connector and a good ground. There should be no continuity.
  4.  



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Fig. Fig. 9 Carburetor switch location on the 1.7L



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Fig. Fig. 10 Carburetor switch location on the 2.2L

COOLANT SWITCH
  1. With the key OFF , disconnect the wire from the coolant switch.
  2.  
  3. Connect one lead of an ohmmeter to a good ground, on the engine.
  4.  
  5. Connect the other lead to the terminal of the coolant switch. On a cold engine, below 150°F (66°C) continuity should be present at the coolant switch. If not, replace the switch. On a warm engine above 150°F (66°C) or on an engine at operating temperature, with the thermostat open, the ohmmeter should show no continuity. If it does, replace the coolant switch.
  6.  

START-UP ADVANCE

For vehicles built in 1978-79, follow this procedure:

  1. Connect an adjustable timing light to the engine so that the total timing advance can be checked.
  2.  
  3. Connect a jumper wire from the carburetor switch to a ground.
  4.  
  5. Start the engine and immediately adjust the timing light so that the basic timing light is seen on the timing plate of the engine. The meter (on the timing light) should show an 8° advance. Continue to observe the mark for 90 seconds, adjusting the light as necessary. The basic timing signal over a period of about one minute. If not, replace the Spark Control Computer and recheck. If it is ok, go on to the next test. Do not remove the timing light or jumper wire. They will be used for the next test.
  6.  

SPEED ADVANCE

For vehicles built in 1978-80, follow this procedure:

  1. Start and run the engine for 2 minutes.
  2.  
  3. Adjust the timing light so that the basic timing is shown at the timing indicator. Additional advance shown on the timing light meter should be:

    0-3° @ 1100 rpm
     
    8-12° @ 2000 rpm
     

  4.  

If not, replace the spark control computer and repeat the test. If as specified, go to the next test.

SPARK ADVANCE

For vehicles built in 1980 on, follow this procedure:

  1. Check basic ignition timing and adjust if necessary.
  2.  
  3. Run the engine to obtain normal operating temperature. Check the operation of the coolant temperature sensor, refer to the coolant switch test in this section.
  4.  
  5. Remove and plug the vacuum hose at the vacuum transducer.
  6.  
  7. Connect an auxiliary vacuum pump to the vacuum transducer and apply 16 in. Hg (54 kPa) of vacuum.
  8.  
  9. Increase the engine speed to 2000 rpm, wait one minute then check specifications.
  10.  


WARNING
The advance specifications are in addition to the basic advance.

  1. If the computer fails to obtain the specified settings, replace the Spark Control Computer.
  2.  

VACUUM ADVANCE

For vehicles built in 1979-80, follow this procedure:

The program for each computer is different. Specifications for individual computer numbers are:



18-22° @ 2000 rpm (all part numbers)
 
23-27° @ 3000 rpm (nos. 5206721, 5206784 and 5206793)
 
28-32° @ 3000 rpm (nos. 5206785 and 5206790)
 

While performing these tests, use a metal exhaust tube. Use of rubber tube may cause a fire due to extremely high temperatures and a long test period.

If the spark control computer fails to meet these tests, it should be replaced.

  1. Connect an adjustable timing light and tachometer.
  2.  
  3. Start the engine and warm it to normal operating temperature. Wait at least 1 minute for start up advance to return to basic timing. Place the transaxle in Neutral and apply the parking brake.
  4.  
  5. Check, and, if necessary, adjust the basic timing.
  6.  
  7. Remove the vacuum line from the vacuum transducer and plug the line.
  8.  
  9. Ground the carburetor switch.
  10.  
  11. Increase the engine speed to 1100 rpm.
  12.  
  13. Check the speed advance timing.
  14.  
  15. Increase speed to 2000 rpm. Remove the carburetor switch ground and connect the vacuum line to the vacuum transducer.
  16.  
  17. Check the Zero Time Offset. Timing should be:

    6-10°-computer number 5206721
     
    2-6°-computer number 5206784
     
    3-7°-computer number 5206785
     
    0-3°-computer number 5206790, 5206793
     

  18.  
  19. Allow the accumulator in the computer to clock-up for 8 minutes.
  20.  
  21. With the accumulator clocked-up and the speed at 1100 rpm, check the vacuum advance. It should be 0-3° at 1100 rpm.
  22.  
  23. Disconnect and plug the vacuum line from the transducer and increase the engine speed to 3000 rpm. Note the speed advance timing.
  24.  
  25. Reconnect the vacuum line to the transducer and recheck the vacuum advance.
  26.  
  27. Return the engine to curb idle. Connect the wire to the carburetor switch if applicable.
  28.  

FUEL INJECTION



Spark Test
  1. Remove the coil wire from the distributor cap and hold it cautiously about 1 / 4 in. (6mm) away from an engine ground, then have someone crank the engine while you check for spark.
  2.  
  3. If you have a good spark, slowly move the coil wire away from the engine and check for arcing at the coil while cranking.
  4.  
  5. If you have good spark and it is not arcing at the coil, check the rest of the parts of the ignition system.
  6.  

Failure To Start
SINGLE MODULE ENGINE CONTROLLER (SMEC)
  1. Test for spark at the coil.
  2.  
  3. Determine that the battery has sufficient voltage, (12.4 volts) for the cranking and ignition systems.
  4.  
  5. Crank the engine for seconds while monitoring the voltage at the coil positive (+). If the voltage remains near zero during the entire period of cranking, check the Single Module Engine Controller (SMEC) and the auto shutdown relay.
  6.  
  7. If the voltage is at ""near battery" voltage and drops to zero after 1-2 seconds of cranking check the distributor reference pickup circuit to the SMEC.
  8.  
  9. If the voltage remains at ""near battery" voltage during the entire 5 seconds, with the key OFF , remove the 14-way connector from the SMEC. Check the connector for any spread terminals.
  10.  
  11. Remove the lead-to-coil (+) and connect a jumper wire between battery (+) and coil (+).
  12.  
  13. Using a special jumper, momentarily ground the terminal no. 12 of the 14-way connector. A spark should be generated when the ground is removed.
  14.  
  15. If the spark is generated, replace the SMEC.
  16.  
  17. If no spark is seen, use the special jumper to ground the coil (-) terminal directly.
  18.  
  19. If spark is produced, repair the wiring harness for an open condition.
  20.  
  21. If no spark is produced, replace the ignition coil.
  22.  

SINGLE BOARD ENGINE CONTROLLER (SBEC)
  1. Test for spark at the coil.
  2.  
  3. Determine that sufficient battery voltage (12.4) volts is present for the cranking and ignitions systems.
  4.  
  5. Crank the engine for 5 seconds while monitoring the voltage at the coil (+). If the voltage remains near zero during the entire period of cranking, check the SBEC and the auto shutdown relay.
  6.  
  7. If the voltage is at ""near battery" voltage and drops to zero after 1-2 seconds of cranking check the distributor reference pickup circuit to the SBEC.
  8.  
  9. If the voltage remains at ""near battery" voltage during the entire 5 seconds, with the key OFF , remove the 60-way connector from the SMEC. Check the 60-way for any loose terminals from the connector.
  10.  
  11. Remove the lead-to-coil (+) and connect a jumper wire between battery (+) and coil (+).
  12.  
  13. Using a special jumper, momentarily ground the terminal no. 19 of the 60-way connector. A spark should be generated when the ground is removed.
  14.  
  15. If the spark is generated, replace the SBEC.
  16.  
  17. If no spark is seen, use the special jumper to ground the coil (-) terminal directly.
  18.  
  19. If spark is produced, repair the wiring harness for an open condition.
  20.  
  21. If no spark is produced, replace the ignition coil.
  22.  

COMPONENT REPLACEMENT



Hall Effect Pickup
  1. Loosen the distributor cap retaining screws and remove the cap.
  2.  
  3. Pull straight up on the rotor and remove it from the shaft.
  4.  
  5. Disconnect the pickup assembly lead.
  6.  
  7. Remove the pickup lead hold down screw.
  8.  
  9. Remove the pickup assembly lock springs and lift off the pickup.
  10.  



Click image to see an enlarged view

Fig. Fig. 11 Remove the pickup assembly lock springs and lift off the hall effect pickup

To install:

  1. Install the new pickup assembly onto the distributor housing and fasten it into place with the lock springs.
  2.  
  3. Fasten the pickup lead to the housing with the hold down screw.
  4.  
  5. Reconnect the lead to the harness.
  6.  
  7. Press the rotor back into place on the shaft. Do not wipe off the silicone grease on the metal portion of the rotor.
  8.  
  9. Replace the distributor cap and tighten the retaining screws.
  10.  

 
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