I have a question about identifying 2 two wires!! I have a 1991 300D 2.5 Turbo Diesel w124 602 MB. I am trying to install, well i have already installed a aftermarket alarm system in it, remote lock/unlock and a remote start.
In the remote start part i have to yet identify two wires from the car.
1.Accessory wire
2. Tachometer wire
Isn't accessory wire any wire that has power (12v) when the ignition key is turned??? Or is it a specific kind?? The instructions point to a pink/red wire on the ignition harness but that is too difficult to get to what else can i use for an accessory wire??
As far as the tach wire (black color) where is the easiest place to tap on to it?? where can i find it at?? the instructions point behind the instrument cluster but i am not about to rip the whole dash out for that. where does the tach wire comes from the undercarriage of the car since i have the car up for some mechanic work as well.
Where is the diagnostic plug in this vehicles at? i know they dont have a ODBII but they have to have some other kind? Installation instructions point to 2 places for the tach wire behind instrument cluster or diagnostic plug or they say you can also use the fuel injector wire but it doesn't tell me which one of those wire.
Sorry for the dumb questions but its a learning process for me
thank you in advance
Denis

The test socket is on the right side of the engine bay near the battery. Look for a black rectangular socket held to the false firewall with a bracket and, probably in your car, having a cover. The tach signal will be on one of those pins.

Locating an "accessory" wire is simply a job of looking for a black or black/red, black/violet striped wire, then testing to make sure it gets 12V when the key switch is turned on.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Should have the correct wiring diagram here.
http://www.tune-town.com/free/mercedes/mercedeshref.htm

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It's always something simple
91 300D 603.960 (from japan) 194K
92 Toyota Diesel Landcruiser HDJ81-t 116K
02 Golf TDI new head courtesy of PO
87 300D
97 BMW 525 TDS Wagon 5spd
bunch of Onan and other diesel generators

Thank you gentleman i will be looking at this on Sunday. What do they mean by "coil"??? You can also find the tach wire at the left inner fender "Coil Left Inner Fender"
Thats where my wire that i put from the inside of the car through the firewall is at right now (at the left inner side) but i dont know what they mean by coil??
thank you
Denis