I have a 92 300SD and on idle is abouth 800 rpm but on gear is about 600 rpm. becouse low rpm the charging light keeps fliking. I been reading about the adjustment for ELR and IP pump, I don'e see the ELR on the engine compartment. There is a plug on driver side on the fender is a plug for testing and try to pull so perhaps rotate and is solid, I do no see the ELR on this car. Any ideas will be appreciate. Thank you guys.

Idle is supposed to be 610 RPM in your car:

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

If you are getting a flickering charge light at 600 RPM you should first check the regulator; maybe your brushes are about worn out. The regulator is part of the alternator and easily accessible from under the car. You do not need to remove the alternator. There are many threads on this forum covering the topic. New regulators are about $50 from FastLane (click on Buy Parts at the top of this page -- they support the forum).

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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

I did check the regulator. At idle is 13.7 and at 2000 rpm is 14.2 Alternartor has about 17k miles on it. I tough may be the ELR started acting up, but I don,t know if this model is equipt with it.