GM Cadillac Deville_Fleetwood_ELD_Seville 1990-1998

Diagnosis and Testing

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VISUAL INSPECTION



On of the most important steps in the diagnosis of a problem is a visual underhood inspection. This can often fix a problem. Inspect all vacuum hoses for pinches, cuts, or disconnections. Inspect all wiring in the engine compartment for good, tight connections. Inspect all wiring for burned of chaffed spots, pinches, or contact with sharp edges or hot exhaust manifolds. These quick tests take only a few minutes but can save you valuable time, and help you repair the problem.

  1. Inspect all vacuum hoses for being pinched, cut or disconnected. Be sure to inspect hoses that are difficult to see such as beneath the upper intake, generator, etc.
  2.  
  3. Check for proper ground connections, ground eyelets connected to ground points and star washer installation, if applicable.
  4.  
  5. Check both battery positive junction blocks for loose retainer nuts.
  6.  
  7. Inspect other wiring in the engine compartment, bad connections, burned or chaffed spots, pinched wires or harnesses contacting sharp edges or hot exhaust manifolds.
  8.  
  9. Check for blown or missing fuses; or relays missing or installed in the wrong locations.
  10.  
  11. Inspect plug wires for proper routing, connection, cuts, or visible signs of arcing to ground.
  12.  

COMPONENT TESTING



Hall Effect Switch
4.5L ENGINE
  1. Detach the wiring connectors at the distributor cap.
  2.  
  3. Turn the four screws and remove the cap and coil assembly from the distributor lower housing.
  4.  
  5. Inspect the interior and exterior of the cap for signs of tracking. If tracking is present, replace the cap.
  6.  
  7. Connect a 12-volt source and ground, and a voltmeter to the switch as shown. Be careful to observe the polarity shown in the illustration or damage to the Hall Effect switch may occur.
  8.  
  9. Without the blade in the switch, the voltmeter should read less than 0.5 volts. If not, the Hall Effect switch is defective.
  10.  
  11. With the blade in the switch, the voltmeter should read within 0.5 volts of battery voltage. If not, the switch is defective.
  12.  



Click image to see an enlarged view

Fig. Testing the Hall Effect switch-4.5L engine

4.9L ENGINE

The distributor must be removed from the engine in order to perform this procedure. Refer to the distributor removal procedure.

  1. Detach the wiring connectors at the distributor cap.
  2.  
  3. Turn the four screws and remove the cap and coil assembly from the distributor lower housing.
  4.  
  5. Inspect the interior and exterior of the cap for signs of tracking. If tracking is present, replace the cap. Connect a 12-volt source and ground to the distributor base 3 wire connector, as illustrated.
  6.  
  7. Attach the voltmeter positive test lead to terminal E of the five-wire distributor harness connector. Attach the negative test lead to terminal D of the five-wire distributor harness connector.
  8.  
  9. Rotate the distributor shaft and observe the blade passing through the Hall switch. Note readings on voltmeter during the shaft rotation.
  10.  
  11. Without the blade in the switch, the voltmeter should read less than 0.5 volts. If not, the Hall switch or harness is bad.
  12.  
  13. With the blade in the switch, the voltmeter should read within 0.5 volts of battery voltage. If not, the switch or harness is bad.
  14.  
  15. Check the harness and retest. If the problem still exists, replace the switch.
  16.  



Click image to see an enlarged view

Fig. Attaching 12-volt battery and ground to the distributor base 3-wire connector

Pick-Up Coil


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Fig. Pick-up coil testing-4.5L and 4.9L engines

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the wiring connectors at the distributor cap.
  4.  
  5. Turn the four screws and remove the cap and coil assembly from the distributor lower housing.
  6.  
  7. Remove the retainers and the rotor assembly from the shaft.
  8.  
  9. Remove the pick-up coil leads from the module.
  10.  
  11. Connect an ohmmeter as shown in Test 1 and Test 2 of the illustration.
  12.  
  13. Observe the ohmmeter while flexing leads by hand. This will check for intermittent shorts (test 1) or intermittent opens (test 2). Compare the obtained reading with the desired results:

    Test 1-should read infinite at all times
     
    Test 2-should read steady at one value within 500-1500-ohm range.
     

  14.  
  15. If test results are not as specified, replace the pick-up coil.
  16.  

 
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