Jump to content


Photo

Testing 59/65 Dm4 Distributors Diagnosis & Repair


  • Please log in to reply
1 reply to this topic

#1 KernowCooper

KernowCooper

    Sparkie

  • Mini Docs
  • PipPipPipPipPipPipPipPipPipPip
  • 7,847 posts
  • Name: Dave
  • Location: The South West
  • Local Club: Kernow Mini Club

Posted 26 March 2013 - 07:01 PM


We see lots of question here on how to trouble shoot Ignition problems on the Lucas OE Electronic Distributors, well I have researched and compiled a step by step on Diagnosis and Repair.

 

Before condemning the external Module remove the cap and check the lobes  inside the dizzy on the rotor have not moved or broken. The pickup coil still shows the right resistance as it's undamaged electrically, but twisted out of shape having been smashed by the rotor. The dizzy fails to flash the test lamp, so people buy a new and expensive amplifier which doesn't fix the problem because there is still no current on the pickup for the amplifier to detect.

 

Models fitted with 59 DM4 distributor
1 Is the reluctor air gap set to the specified dimension? between pickup and magnet Air gap = 0.006 to 0.010 in (0.15 to 0.25 mm) 59/65 DM4

2 Is the battery voltage greater than 11.5 volts? If not recharge battery before doing the tests

3 Is the voltage at the coil “+” terminal more than 1 volt below battery voltage? If so check all connections for corrosion/loose terminals from ignition switch out to coil +

4 Is the voltage at the coil “-” terminal more than 2 volts? If so disconnect the wiring connector between distributor and ignition
amplifier and proceed to Test 7 If No disconnect the ignition amplifier lead at the coil “-” terminal and
proceed to Test 5

5 Is the voltage at the coil “-” terminal now more than 2 volts? If so proceed to test 6 If not replace the Coil

6 Is the voltage at the ignition amplifier earth more than 0.1 volts? Yes clean and/or repair the earth connection No: Renew the ignition amplifier

7 Is the pick-up coil resistance measured at the wiring connector ignition terminals between 2.2k ohms and 4.8k ohms? Yes:Reconnect the wiring connector between distributor and amplifier and proceed to Test 8 No: Renew the pick-up coil assembly in the distributor

8 Does the voltage at the coil “-” terminal drop when the starter motor is operated? Yes: Check and adjust the ignition timing. If the fault still exists the
problem may lie with the engine internal components No: Renew the ignition amplifier

Models fitted with 65 DM4 distributor
1 Is the battery voltage greater than 11.7 volts? Yes:Proceed to Test 2 No: Recharge the battery

2 Is the voltage at the coil “+” terminal within 1 volt of battery voltage? Yes: Proceed to Test 3 No: Faulty wiring or connector between ignition switch and coil, or faulty ignition switch

3 Is the resistance between the ignition coil “+” and “-” terminals between 0.4 and 0.9 ohms? Yes: Proceed to Test 4 No: Renew the ignition coil

4 Is the resistance between the ignition coil “+” and HT terminals between 5.0 and 15.0 k ohms? Yes: Proceed to Test 5 No: Renew the ignition coil

5 TO TEST THE MODULE Connect a low-wattage bulb across the ignition coil “+” and “-” terminals and spin the engine on the starter. Does the bulb flash?
Yes:Proceed to Test 6 No: Proceed to Test 10

6 Is the resistance of any HT lead greater than 20 k ohms? Yes: Renew the HT lead No: Proceed to Test 7

7 Are there signs of tracking on the ignition coil, distributor cap or rotor arm? Yes: Renew the component as necessary No: Proceed to Test 8

8 Is the ignition timing correct? Yes: Proceed to Test 9 No: Adjust ignition timing

9 Are the spark plugs in good condition? Yes: No: Renew the spark plugs

10 Are the module connections good? Yes: Proceed to Test 11 No: clean as required if module connections damaged replace module

11 With the module removed, is the resistance of the distributor pick-up coil between 950 and 1150 ohms? If not renew the pick up coil.


Could this be pinned ?


Edited by KernowCooper, 15 November 2014 - 04:18 PM.


#2 KernowCooper

KernowCooper

    Sparkie

  • Mini Docs
  • PipPipPipPipPipPipPipPipPipPip
  • 7,847 posts
  • Name: Dave
  • Location: The South West
  • Local Club: Kernow Mini Club

Posted 26 March 2013 - 09:32 PM

Part 2 to follow will be testing aftermarket Electronic Hall Effect Ignitions




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users