[carsben353]

Car cut off at the gas station a few weeks back. Jumping it gave it enough power to get 5 miles with the headlights on. Alternator was bad. changed the alternator. Still have a problem. Car will run forever with no heat or headlights, as soon as the extra load is added the abs light comes on. many times the abs light will shut off if the extra load is removed. I know the abs light is the first indicator of an extremely poor charrge in the system. I have had the alternator tested 6 times on 3 different occasions all of the tests say it is fine. I am getting 14.x volts out of the alternator installed on the car. The battery has been tested fine. I have replaced the ovp, all belts (to ensure good tension), and all the fuses with the copper style. I dont know if this is significant but the charging dummy light never seems to come on, just the abs light. What am I missing? I have to trickle charge the battery every few days. This has been going on for weeks.

 

[JW560sec]

I believe thhe voltage regulator is seperate from the alternator on these cars. I could be wrong. I wanna say its right next to it. Did you by chance already replace or test? Possibly a short in some wiring, draining battery. Does it drain overnight?

 

[carsben353]

will not drain overnight. I believe the voltage regulator is in the alternator.

 

[Grumpy560]

strange. never had a problem like this on my 560. but I did check the voltage just to see what was going on anyway. I had 14.6V at the battery while engine was at Idle and in park without any accessories on. then with all accessories on I had 13.2V at battery. how did you check the voltage? you must check it at the battery, not the alternator. are the battery terminals and cables clean from corrosion. whne you replaced the ALT did you get the correct replacement(correct AMP)I would check the battery to chassis ground first and make sure both ends are making good contact. the alternater may be charging but that current may not be reaching the battery correctly. thus the reason for no charge light in dash. FYI batteries can develope a dead cell or 2 and when checked at auto parts stores, dead cells can go undetected due to the way most of them are fast charged if brought in half dead to begin with. so swapping out the battery with a known good one is what I would do after I checked all other connections first.

 

[carsben353]

even with a bad battery, shouldnt the alternator be able to run the car without issue with acc.? Just not restart it. I had the alternator belt blow 13 months ago and the battery light came on. Does this mean the alternator is actually functioning? The cables out of the alternator and at the battery read 14.X. I believe the alternator is 80 amp. presuming the ignition is 20 amps, the radio is 10 amps, the headlights are a total 20 amps and the heat is 20 amps (amperage is guesstimate dnt have the #'s in front of me) There shld be 10 amps to spare. I have unplugged the power antenna and insured the rear defrost is off (at least at the switch)and the sunroof seems to function normally ( all are high amperage acc.) What cld be unnaturally drawing so much amperage only when the car is running to cause this problem? How do I find it if a hot at all times draw is the issue?

 

[mvmiller]

When you replaced the alternator was the battery charged above 12.9 volts? If not you may have damaged the new alternator rectifier and orthe regulator located on the outside of the alternator.
It is very important that the battery was charged at least to that level before you replace the alternator.
The ABS light comes on if the battery voltage drops below 10.5 volts. That indicates to me that you may have a faulty cell in the battery. Each cell is aprox 2 volts. There are 6 plugs or cells in a 12 volt battery. Have them do a charge test (load) as well as the potential test
I would have the battery rechecked. The attachment is from the AlldataDIY pages.

 

[carsben353]

When you replaced the alternator was the battery charged above 12.9 volts? If not you may have damaged the new alternator rectifier and orthe regulator located on the outside of the alternator.
It is very important that the battery was charged at least to that level before you replace the alternator.
The ABS light comes on if the battery voltage drops below 10.5 volts. That indicates to me that you may have a faulty cell in the battery. Each cell is aprox 2 volts. There are 6 plugs or cells in a 12 volt battery. Have them do a charge test (load) as well as the potential test
I would have the battery rechecked. The attachment is from the AlldataDIY pages.

where is the external voltage regulator located? I have had the battery tested since the alternator replacement and it still tests good.

 

[mvmiller]

The regulator is attached to the alternator. It looks like this: It is about $26.00 at autohausaz.com

 

[carsben353]

that regulator was new with the alternator and it is the only reulator I know of. An earlier post seemed to imply there were 2.

 

[mvmiller]

Then it may be in the cables themselves. You may have a corroded cable, connecting block, or terminal connection. Also check the braided grounding strap located between the the dirvers side fender well and either the power steering or AC mounting bracket. This strap can become deteriorated over time.

Actually measure the cables completely disconnected at both ends. Also measure the cables coming from the alternator to the terminating block on the firewall which connects to the battery terminals. You should measure zero ohms or very close to zero. If the cable(s) measure 1 or more ohms that would cause a current draw and a voltage drop. Remember to flex the cable back and forth(gently) as you are measuring to make sure it is giving you a true reading. Remember all of these cables have been moved around recently during the replacement of parts so... I had a faulty cable that measured 2 ohms cause an electrical "failure" in my daughters 86 190E. Keep in mind these are "old balls" cars. Wiring does fail, eventually.

Sometimes the wires will have "warm spots" on them. Feel them as the car is running.(One hand only and with rubber souled shoes on!) That could also give you a clue if the cable has a "voltage drop" (resistance or impedance) inside of it.

 

[carsben353]

checked the resistance and continuity of the alternator cable. Good continuity and no draw. retightened all the connections and ran the car for 20 minutes with blower and headlightrs running without the battery dropping below 12 volts(prompting the abs light). I am still extremely skeptical as the car has acted this way before for 6 days before acting up again. we will see.

 

[carsben353]

abs light finally came on. More ideas would be grateful.

 

[mvmiller]

There is a 3 wire connection that is piggybacked onto the positive battery terminal. This piggyback is the voltage feed to the OVP relay. Sometimes this connection gets corroded and can cause the OVP relay to appear defective when in fact the voltage drop will throw an ABS error code. The OVP IS the ABS relay. Check the OVP connections plug for corrosion etc...

One of the forum members, Abdullah2009 had a similar issue in regards to the ABS light coming on and it was the piggyback wire harness whuch goes directly to the OVP relay connector. with this type of problem it appears to look like an OVP relay failure when it is really inadequate voltage to operate the relay properly. His problem also manifested as a high idle and an ABS light going off and on,
Here is the link to the fix. Hope this helps
http://www.benzworld.org/forums/w126-s-se-sec-sel-sd/1494086-abs-bulb-idle-high.html

 

[carsben353]

replaced ovp connections at the battery and checked the connections at the ovp. there was no corrosion. abs light still comes on after a while under amperage load. Checked the battery with abs light on 10.8v checked the alternator power lead with abs light on 10.8v checked the power at the ovp (fuse) same. Sometimes it would dip to mid 9v depending on the accesories i was running. Here is the strange thing when I shut the car off with the abs light on the battery will read mid 10v yet the car will start back up, pretty quickly. I always thought the starter needed 12 volts. Any more ideas would be great.

 

[NordRhein]

IF the positive lead to the battery is ok and the ground cables are ok then that leaves two things. Either the alternator brushes are losing contact (or similar thing which would shut it down) or the alternator is being told to turn off.

 

[mvmiller]

I agree with NordRhein,
I know I stated this before ...
When you replaced the alternator was the battery charged above 12.9 volts? If not you may have damaged the new alternator bridge rectifier and or the regulator located on the outside of the alternator.
It is very important that the battery was charged at least to that level before you replace the alternator.

It is possible you have a defective replacement alternator. Based on your last post, that is what it sounds like.

 

[carsben353]

well i got another new alternator, the bosch al129x 115amp alternator. I made sure the battery was fully charged and installed it. Same problem. abs light eventually comes on, headlights are dim, blower barely blows ect.

 

[RickASolis]

i thought the 126 only came with 70 and 80 amp alternators??


anyway its possible to get a defective alternator. I got one from auto zone (yeah...i know), made in Mexico cheapie. Right in the middle of a 300 mile trip at 2am, i had to pull over because of this strange odor. The alternator was cooking my battery. the vent tube was pouring out gas and smoking like crazy. The alternator was overcharging big time. I took it back and they gave me another one, rebuilt in Germany (at least that's what it said). came with a nice paper showing readings from the test, and it just felt of better quality. haven't had a problem yet. also batteries do very strange unusual things, replace it with a known good one i bet it goes away

 

[JW560sec]

checked the resistance and continuity of the alternator cable. Good continuity and no draw. retightened all the connections and ran the car for 20 minutes with blower and headlightrs running without the battery dropping below 12 volts(prompting the abs light). I am still extremely skeptical as the car has acted this way before for 6 days before acting up again. we will see.

Did you perform this test while the car was running?
Was your replacement OVP mentioned, new? Or used?
Have you checked your battery to see if it might new some electrolyte fluid?
Checked for wiring ANYWHERE that might be broken and grounding?

 

[carsben353]

Did you perform this test while the car was running?
Was your replacement OVP mentioned, new? Or used?
Have you checked your battery to see if it might new some electrolyte fluid?
Checked for wiring ANYWHERE that might be broken and grounding?

The ovp was used. I did the continuity and resistance test with the car off and wires disconnected. The only wire I did not do these tests to was the starter wire. The battery has been tested multiple times.