Good work! Does the GP lamp on the dash now lights up for a timed period, and then go out, as it should?
As others have said, this is not quite 'fine.' Proper reading should be 0.8 to 1.2 ohms, connecting from each socket to ground, which measures the resistance of the GP & the wire, and the wire is essentially 0.0 ohms.
Yes, the wires could be corroded, or they could be broken.
You mentioned that three show an 'infinite' reading. An 'infinite' resistance is an open wire, the opposite of no resistance. Mis-typed?
Yes, they are in parallel, not in series.

I am puzzled, though, since you said it started 'like a champion' but are convinced that only 2 out of 5 GPs are functioning... Something is not quite right here... It sounds like all 5 are working, since it starts quickly, but there may be a flaw in your measuring, or in describing what you are measuring...

Please verify that you are measuring resistance from each socket in the connector to chassis ground.

To check the wires, connect the ohmmeter from each socket to the tip of the respective glow plug. It should read 0.0 ohms or so. If it reads 'infinite' it could be a broken wire, open connector, or other break.

Best Regards,
Jim

Your GP should be individually wired from the relay so as my 80 300SD. The older engines has a common power rail that connects all 5 plugs together.
My #4 GP has no power supply to her too. Now I did jump another wire from #2. The first starting is much easier now.


I hate working even the terminal bolt. Its so cramped for space. They think we have midget hands!
Plus the surrounding are qute sharp to cut your nitryl gloves too.

Yes, it lights up for about 5 seconds and then goes out. It is about 90 degrees out, so that is probably normal.

I am probably using the multi-meter incorrectly. What setting should I use? It ranges from 200K to 200 on mine, and I don't understand the difference. I am putting the black to the battery negative and the other wire I am putting into the controller that I deattached. The controller has six numbered pins but only five have a metal lining. So I am assuming this is where I should put the multi-meter.

Anything sound wrong here? The readins I am getting are around 7.8 and 26 something at the 2000 setting for pins 1 and 3. The rest show 1, which is the same reading the multimeter gives if nothing is attached.

-Travis

Yes, it sounds like all 5 GPs are now correct.

By the way, you may, if you like, wait longer after the lamp goes out. The GP relay will keep power on the GPs after the lamp goes out, for 30-45 seconds or until you turn the key. Sometimes a little extra time, especially in colder weather, helps the starting.
Ohm scales are 'understood' to be 0-RANGE, such as 0-200, 0-200,000 (200k) etc. Since you are looking for a range of about 0.8 to 1.0, the 200 (smallest) would be appropriate.
The meter measures the resistance of a circuit connected between the red and black leads. You want the resistance of the GP, so you want the leads to measure from 'ground' (one side of the GP is grounded through the shell) and the GP wire terminal.

(By the way, it does not matter if the black or red leads are 'ground' for resistance measurement, but it does matter for voltage. A good habit is black=ground, red=hot, so you are correct.)

You can check the GPs that you removed. Clip the red lead onto the wire terminal and touch the black lead to the threaded shell. A good GP will read 0.7-1.0 or so, a bad GP will probably read infinite.

In-vehicle testing is straight forward. Black to battery negative, or 'chassis ground,' or any bare metal of the engine or the body. You then touch or clip the red lead to the wire terminal of each GP to get a reading.

Or, you can clip the red lead to the GP terminal, and touch the black lead to ground.

A convenient method is to touch the red lead to each of the 5 sockets (metal shells that fit over posts on the relay) in the GP wiring connector after it is removed from the controller, since each wires is connected to a GP terminal. That way, you don't have to lean over the engine, touch the terminal, balance the meter and try to read it without breaking contact!

To complete your testing, clip a lead to the GP wire terminal, and touch the corresponding socket in the connector. This reading will tell you the resistance of the wire from the GP to the connector. The reading should be 0.0, or 0.1. Anything higher could indicate a corroded or broken wire.

It is far easier to demonstrate and perform in person.

I hope this explanation makes sense.

Best Regards,
Jim