When I started my car today the engine wouldn't idle right. It would surge to 2000 rpms and then almost die. It did that till I held it at 2000 rpms for a little while then idled ok. The air pump was also cycling on and off. I did some errands it ran good although the radio would come on and go off on its own and I had no cruise. I got code 15 from the built in diagnostic module(injector,cylinder 2) and a code 49 from pin 8(voltage supply at engine control module implausible/low volts)
Would pin 8 code point to a bad alternator?
would the built in module code point to a bad injector.
Thanks for any input.

ABS lamp ON ??

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A Dalton

No ABS lamp or any other now. I did have a running light out(back right)replaced it and the lamp went out. Thanks Arthur

Pull the OVP and see if it is 000-540-52-45..
If it is , change it to the new part # 000-540-67-45
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Take a battery reading, both off and running, to make sure we have adequate power and charge.

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A Dalton

The OVP has the new number on it. I got a little over 12 volts not running and 17 volts when the car was running.
Thanks Arthur

I think you have a Voltage regulator problem.

You sure about that 17V reading??

If YES, then change the regulator on the back of the Alt.
And don't run the car much in the meantime b/c you can fry some expensive parts at 17V. That is prolly what burnt the rear lamp. The OVP is dropping V to Engine systems b/c of over-voltage from Alt [ now you know what an Over-Voltage-Protection relay is there for ]

After the change , take another running V test and check all fuses ..and give all fuses a spin in their connectors too.

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A Dalton

I rechecked voltage with car running and got 17 volts with my analog meter. Can you tell me where the voltage regulator is or is it part of the alternator?
Thanks Arthur

On the back of the ALT..couple of screws an it pulls right out..simple DIYer.

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A Dalton

Thank you so much for your time and information Arthur,take care
L. kelley

You're Welcome.

Post final results when you get them.

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A Dalton

Arthur, I don't believe a 1994 E320 alternator has the removable voltage regulator on the back like the older 124 cars.

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Fred Hoelzle

I think you are correct..I have seen both, but many may have been rebuilts already changed..he will know when he looks at it.

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A Dalton

My 1994 E320 has a voltage regulator on the back of the alternator. in fact it is the same PN as the one on my 1993 300E. I think the change came later in 1994 with chassis #C17XXXX.

I think that was a mid year change b/c I also have a '94 right here with removable Regulator too...........

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A Dalton