Austinsec

Anyone know how to check what the voltage coming out of the alternator is.
I got the xentry system today with the car on my batt goes from 14v to 10 after some time. then i get votage error.
I bought a new regulator deciding weather to install or is it something else.

ygmn

voltmeter

mikefamig

Conet the + and - leads of your volt meter to the + and - posts of the battery, Have someone start the engine while you are watching the volt meter. the voltage should increase when the engine starts indicating that the alternator is charging the battery. If the voltage just decreases then your alternator is not charging the battery.

You might want to try this on another car that is working properly to see what it should look like.

Mike.

Austinsec

I know it is not charging the question is how do I know if it is the alternator or the regulator?

A1EK

With engine off, the battery should read around 12.5V
With engine on, charging voltage should be around 14.1V regardless of load (lights, heater) the voltage regulator maintains the Volts by definition.

Just stick a multimeter on your rear battery and start the engine.

Austinsec

It does not maintain it keeps dropping until not enough to drive. How do I determine alternator or regulator?

mikefamig

In the old days of mechanical regulators you would just connect the field terminal of the alternator to ground which would send the alternator into full charging output increasing voltage at the battery. If grounding the field terminal does not raise voltage then the alternator has a problem. Even if you could find the field terminal on your R230 alternator I would hesitate to strap it to ground for fear of damaging a sensitive electronic component.

In any case the regulator is probably inside the alternator case so the alternator will need to be removed for repair.

This may help

https://mbworld.org/forums/sl-class-...lator-diy.html

Mike.

Austinsec

so I bit the bullet and attempted to replace the regulator. sadly the screws that hold the regulator 2 of the 3 are stuck and I am doing it under the car any advice?

mikefamig

Use a long handled wrench and instead of pulling on the wrench handle, rap the handle with a hammer. This will often break a stuck screw loose. Heating up the engine might also help.

I just did some reading online and I learned that the regulator has contact brushes that wear with time so it's a good idea to change it as a matter of course after 100k miles or so.

Mike.

Austinsec

the screws are philips got one more loose , last one is the one towards the top not way to reach with 2 hands for tapping

mikefamig

Worst case remove the alternator. It's better than damaging the alternator.

mikefamig

Do you have enough space to use a 1/4" drive ratchet wrench with a phillips head screwdriver tip?

Austinsec

yes but it seems srtipped Ill try again
Anyone on long island that is handy that can help switch regulator on alternator , I have bottom 2 screw out but the final one is stuck. Im on exit 39. thank you

A1EK

ratchet with Philips is a good idea, have you tried using a rubber band on the stripped head trick?
otherwise use an easyout tool

You may find once you have the regulator off, the brushes have just worn ?

mikefamig

If the alternator were on the workbench you could break the plastic body of the regulator exposing the screw shank so that you could use a vise griip pliers to remove it.

Mike.

EDIT - Also ii the alternator were on the bench I'll bet that you would be able to remove the screw with a screwdriver.