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1992 400E
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Discussion Starter · #1 ·
So I have a newly rebuilt alternater, good battery, turn key click. I can sit there and after ruffly 20 seconds starter gets moving and car starts. No charge being seen at battery.
Can't find anywhere to buy the 2 lower harnesses. Can I dyi it?
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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The lower harness is now NLA, so a rebuild us in order. It is a simple harness to DIY. Replacement wire can be found at auto parts houses. You'll want to be sure and get the correct gauge wire and heat resistant insulation. If you're handy with a soldering iron it is a straightforward project.

Does the no start issue also occur when you have the gear selector in neutral?

Good luck

Jayare

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There is only 1 lower harness. As Jayare said, it's NLA new. You can rebuild it yourself, or buy a rebuilt (with core exchange) from Blue Ridge MB. This harness contains the large wire to the starter and alternator, plus 4 smaller wires for starter solenoid, alternator D terminal, along with oil pressure & level sensors.

What you describe MAY be a failing starter. They don't last forever. If the click you hear is coming from the starter, and if you hold the key in start position it eventually engages, that sure sounds like a failing starter to me.

However, first try what Jayare mentioned about moving the shift lever to Neutral and see if there is any difference.
 

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1992 400E
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Discussion Starter · #4 ·
Thanks I'll check the neutral start tonight. Odd that I can't see the charge system charging at the battery??
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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Thanks I'll check the neutral start tonight. Odd that I can't see the charge system charging at the battery??
What do you mean by "can't see charging system charging the battery"?

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1992 400E
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Discussion Starter · #6 ·
I have a battery tester that I can put a load on it and I can also see whether this system is charging at the battery
 

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You should see 13.5-14.5 volts at the battery with the engine running.

If you are measuring 12.5 volts or less, the alternator is not charging. If the alternator is known to be good, this means the "D" wire (which is part of the lower harness) may be compromised. Check the wiring behind the alternator, if there are bare wires, separate them & insulate them until you are able to remove and repair the harness.

I don't know if a load tester at the battery with the engine running, will work properly or not. Never tried this.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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In all my 55 or so years of turning wrenches I, like gsxr, haven't seen a load tester that also measures running voltage. Any volt meter will give you voltage at the battery.

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Sounds like the starter, or lower harness, or both. Neither are fun jobs.

If the wires behind the alternator are missing insulation, I'd consider doing both at the same time. The harness replacement will be much easier with the starter removed. You could also test the starter outside the car to verify if it's definitely bad.

Also, if you can confirm the "click" is coming from the starter, that's a strong indicator the starter is the culprit.
 

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1992 400E
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Discussion Starter · #11 ·
Car starts right up when jumped. Remove cables can watch battery voltage drop. Alternator not getting to battery. 13 volts at alternater when running, again not getting to battery
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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Change the voltage regulator. It is held in place on the back of the alternator by 2 phillips screws.
 

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1992 400E
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Discussion Starter · #13 ·
I would assume when I had the alt redone he also did the regulator??
 

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You said the alternator was "newly rebuilt", but who rebuilt it? If under warranty, have it tested and replaced.

Also, the symptoms you describe do not make sense. If the alternator is not charging and the battery is weak, holding the key in "start" position for 20 seconds should not engage the starter at all. And when it did engage, the starter would sound weak and spin the engine slowly. Something isn't adding up here.
 

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1992 400E
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Discussion Starter · #15 ·
Local rebuilder been doing it for 30 years. Initially I could drive about 15 minutes then car died. Got it home decision to pull alt. Took it I was all gone. Bearing etc. $80 good as new he said.

Before pulling the alt it would start out slow and build up to eventually start the motor. Battery is 2 years old and was flat out drained so I have been charging it for days. Now turn key, no jump, charged battery click, all dash lights are on. When jumped starts right up. Take of jump, lights stay on gages start to flip all over speedo jumping etc. Voltage drops like a rock on battery. No voltage coming from alt to replenish. I'm ready to just sell her!!!
 

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If you fully charged the battery and it only clicked, then added a jumper and it fired right up, the battery may also be bad. Have the battery load tested.

Again, as mentioned before, the alternator can be perfect but if the lower wiring harness is degraded, it can prevent the alternator from charging because the small wire is not signaling the alternator to charge...
 

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1992 400E
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Discussion Starter · #17 ·
So I took pics of everything except where each pin goes in large fitting that is snapped together up top? Any help
 

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1992 400E
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Discussion Starter · #19 ·
Not sure what the question is... last post a month ago said you had starter problems, what pin/fitting up top are you referring to?
I have rebuilt the lower wiring harness and I'm trying to put the wires that have pins back into the box that then is clipped to another box together by the firewall
 

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I see a lot of input has been provided but not sure of what has been done.

Today's batteries resist being charged once they are fully drained/are flat. Its the nature of the beast. You can't simply hook up a charger and expect the battery to come back to full capability. The best way to know that your battery is in good enough condition to do your diagnostics is to have it load tested. This can be done by your alternator rebuilder guy.

Confirm the battery is at least 90% of potential when taken off the charger, or over night it drops no lower than 75%. If so, then you can move on. Anything else, you have a battery issue. I have had good experience blasting batteries back into life. It takes a charger capable of 80 amps and charging cycles that vary between 2 amps and a few at 80 to wake one of these batteries up.

As far as that connector is concerned, if you still need a photo, let me know. I think you are talking about the three pin connector on the firewall just in front of the brake master/booster.
 
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