hey im doing the same swap in my 88' but I bought the project from some guy that I guess did one before but he didn't have the time to finish the one I bought so I was hoping you could help me out!! I am having a hard time wiring up my glow plug relay...I know where the red tan red w/black stripe purple and blue w/white stripe go but there is a smaller relay thing attached to it that has 3 wires coming out of it and I have no clue where they would go to. I am also having a hard time finding the wires to hook up the alternator properly...what did you do for yours?? close up pics of the wiring for the entire motor would be a great help!!!!!!!! thanks

Powerstroke,
I attached the Glow Plug schematic from the Mercedes 300 manual; it shows how to wire your glowplugs properly. Essentially, the relay is powered up all the time. On my particular install I have the glow plugs powered up manually by a spring toggle on my dash; I didn't want to take chances should the relay fail in the powered up position. In any case, can you send me a photo of your smaller relay w/three wires? Might it be the OEM cruise control?

Ref the alternator; again, I did mine differently. Charging (large gauge wire) goes directly to the battery; the other wire should go to your old battery charge light on the dash. My Ford doesn't have one; all I had to do was to wire it to my orig Ford starter solenoid (hot side, small terminals). Reason: In order for the alternator to function (charge the battery), it needs to "see" some voltage; your charging light does that by completing the circuit with the lightbulb. It is pretty simple...and confusing at the same time...once the alternator sees the voltage at the W terminal aka the small wire, it will charge. You can remove the W terminal wire and the alt will still charge which threw me. Shut down w/o wire attached=no charge. Took me a while to do the 2+2 thing. Should work fine in either case; I was told from a mercedes mechanic that either way works...12 volts is 12 volts!

Whatever you do, make sure your battery stays connected when the engine is running; some folks test voltage output by disconnecting the charge cable...burns the alternator up quickly. I don't recall how much the output is, I'm guessing around 13 to 14 volts..anything above 12 means it is charging the batt. Hope this helps and good luck!

Giacomo

Giacomo, Thanks for the help!!!! ill give it a shot today and ill let you know if I get stuck on anything else...that diagram helps a lott!!!