Testing Trigger Points

[Schroeter]

My test with ohmmeter was successfull. Here's what I did:

Background: W114 Benz with D-Jetronic fuel injection (1969). This system has "trigger points" in the distributor. There is a convenient little "drawer" on the side of the distributor where these points slide out.



You could test the resistance by connecting the ohmmeter to the 3 pin electrical connector and rotating the distributor, but I chose to remove the distributor and pull out the trigger points (3 screws total). Here are the steps:

1- Remove vacuum hose from distributor
2- Remove dist. cap
3- disconnect the Green wire from coil or ignition switch box (depending on your setup)
4- Remove the 10mm/ Flat head bolt (I removed the battery first to gain better access to this bolt with a long wrench to avoid stripping).



Now you can remove the trigger points from the distributor. Pic above shows distributor with trigger points removed already.

5- Remove the 2 flathead screws from the side of the distributor
6- Slide out the trigger points (pull gently on the black electrical connector).




Now you can test the points with an ohmmeter.

7- Set your multi meter to resistance (omega symbol). Connect one test pin to the center (of 3) terminals on the points electrical connector, and the other test pin to one of the end terminals. You should see 1. for open points and 0.00 for closed points (or vice versa - I can't remember/tired/car still not running frustration!).
8- Repeat for other side by keeping one test pin on the center terminal and the other moved to the other side.
9- (important) Repeat this test with the trigger points back in your distributor (so you know if the cam is working properly with the points).


Pic above doesn't show the points contacts but rather the contact point that moves against the cam.

Mine tested fine. If they don't test fine for you, make sure the points close properly, make sure they are clean. If still no luck, keep an eye on this thread, there may be some more suggestions for repairing points. Apparently they are expensive to replace.

Cheers