Red Battery symbol, then abs dsc please help

[StephenVA]

NEVER remove a battery connection when the engine is running. You will not like the results of the surge damage when reconnecting it. Modules will fail, electrical components will go off the deep end. Can it be done and not have any issues? Yes, but why take the chance? THis "test" was a short cut way back in the 60's left over from post war vehicles with generators.

Loose power connections have shorted out more electrical components than anything else in history. (An assumption on my part. No actual data collected...)

Regarding a vehicle that dies when the battery is disconnected: A good electrical system SHOULD have kept it running. But who knows what failed at the same time as the disconnect? The Regulator? The main module? The ground wire? Who knows? Maybe the alternator/wiring was DEAD/shorted before the disconnect.....

[Helihover]

Originally Posted by StephenVA

NEVER remove a battery connection when the engine is running. You will not like the results of the surge damage when reconnecting it. Modules will fail, electrical components will go off the deep end. Can it be done and not have any issues? Yes, but why take the chance? THis "test" was a short cut way back in the 60's left over from post war vehicles with generators.

Regarding a vehicle that dies when the battery is disconnected: A good electrical system SHOULD have kept it running. But who knows what failed at the same time as the disconnect? The Regulator? The main module? The ground wire? Who knows? Maybe the alternator was DEAD before the disconnect.....

It was stated that the connection at the battery came loose. Once tighten all was well from what I remember.

I thought the car should have kept running too.

[jfoj]

The battery dampens and filters the alternator output.

One thing that most modern vehicles do is the DME/ECU can and will kill spark and fuel if the input Voltage gets too high to protect the DME/ECU and other modules in the car in the case of a high Voltage swing. Usually 17-19 Volts it the trip point for most vehicle. No idea the exact value for BMW and I am not interesting in finding out on any of my cars.

You can arc weld with 120-200 Amps and as mentioned it is not a wise test to disconnect the battery on a modern vehicle for testing. Without the battery as a static load and filter, the alternator can do some funny things. Even filtering out AC ripple that can high peak to peak Voltages.

A $20 Voltmeter or using the Hidden OBC Menu to access the Voltage and display it on the dashboard is all that is needed. Charging and starting systems are really easy to trouble shoot as long as the EWS does not get in the way.

Learn how to use a Multimeter/Voltmeter and learn how to perform Voltage Drop testing and you can correct the majority of problems that creep up. I also use a spare pair of jumper cables to connect temporary grounds to identify and find problems.

[StephenVA]

Originally Posted by jfoj

The battery dampens and filters the alternator output.

One thing that most modern vehicles do is the DME/ECU can and will kill spark and fuel if the input Voltage gets too high to protect the DME/ECU and other modules in the car in the case of a high Voltage swing. Usually 17-19 Volts it the trip point for most vehicle. No idea the exact value for BMW and I am not interesting in finding out on any of my cars.

You can arc weld with 120-200 Amps and as mentioned it is not a wise test to disconnect the battery on a modern vehicle for testing. Without the battery as a static load and filter, the alternator can do some funny things. Even filtering out AC ripple that can high peak to peak Voltages.

A $20 Voltmeter or using the Hidden OBC Menu to access the Voltage and display it on the dashboard is all that is needed. Charging and starting systems are really easy to trouble shoot as long as the EWS does not get in the way.

Learn how to use a Multimeter/Voltmeter and learn how to perform Voltage Drop testing and you can correct the majority of problems that creep up. I also use a spare pair of jumper cables to connect temporary grounds to identify and find problems.

[dabenthusiast]

Called AAA today driver came out, I said I want it towed home.
Driver said let me jump it its probably your alternator but if it starts you'll be able to make it home, I said I just want it towed. He said drive it around the corner if it workstill it'll be fine you'll make it.


So I left. Speedo abs hill decent all started going haywire.
Car started braking when driving at 50 MPH and dash all went out speedo dropped then I lost power to car and pulled over.

Tow truck ca.e towed it rest of the way home. I'll do test tomarow. It started to rain and has been a long day .

[Joshdub]

Originally Posted by dabenthusiast

Called AAA today driver came out, I said I want it towed home.
Driver said let me jump it its probably your alternator but if it starts you'll be able to make it home, I said I just want it towed. He said drive it around the corner if it workstill it'll be fine you'll make it.


So I left. Speedo abs hill decent all started going haywire.
Car started braking when driving at 50 MPH and dash all went out speedo dropped then I lost power to car and pulled over.

Tow truck ca.e towed it rest of the way home. I'll do test tomarow. It started to rain and has been a long day .

Yeah as you have learned, never listen to the AAA drivers.

I had to show a AAA driver how to get my car onto flat bed one time. It didn't have a front tow hook so he was just going to use a control arm

[dabenthusiast]

[QUOTE=Joshdub;1062615]Yeah as you have learned, never listen to the AAA drivers.


Yes I have learned my lesson haha. My mistake fully on that. But I did tell him multiple times just to tow it to my house haha he insisted on my driving it.

Looks like my tahoe trip is going to be postponed. But I'm glad it failed here not on a snow trip in the snow haha.

Second guy was all surprised that I already had my tow hook on the car ready to be towed haha

[Joshdub]

[QUOTE=dabenthusiast;1062623]

Originally Posted by Joshdub

Yeah as you have learned, never listen to the AAA drivers.


Yes I have learned my lesson haha. My mistake fully on that. But I did tell him multiple times just to tow it to my house haha he insisted on my driving it.

Looks like my tahoe trip is going to be postponed. But I'm glad it failed here not on a snow trip in the snow haha.

Second guy was all surprised that I already had my tow hook on the car ready to be towed haha

Sucks about the trip man but yeah you are right. Much better to have it fail there than out in the middle of no where

[upallnight]

Originally Posted by StephenVA

NEVER remove a battery connection when the engine is running. You will not like the results of the surge damage when reconnecting it. Modules will fail, electrical components will go off the deep end. Can it be done and not have any issues? Yes, but why take the chance? THis "test" was a short cut way back in the 60's left over from post war vehicles with generators.

Loose power connections have shorted out more electrical components than anything else in history. (An assumption on my part. No actual data collected...)

Regarding a vehicle that dies when the battery is disconnected: A good electrical system SHOULD have kept it running. But who knows what failed at the same time as the disconnect? The Regulator? The main module? The ground wire? Who knows? Maybe the alternator/wiring was DEAD/shorted before the disconnect.....

What we are failing to take into consideration is not just the voltage but the amps draw when Terminator lost power to his X. He was running at night with all the lights on and if it was in the dead of winter he might have had the blower motor on for the heater and imaybe the rear window defroster.

I have driven a car with a bad alternator on a battery as long as any non essential electrical device were left off including the radio. When the alternator to my PORSCHE crap out on me, I brought a new battery but only drove during the daylight hours. I was able to make the 40 miles trip back home on just the battery.

[bcredliner]

Originally Posted by StephenVA

NEVER remove a battery connection when the engine is running. You will not like the results of the surge damage when reconnecting it. Modules will fail, electrical components will go off the deep end. Can it be done and not have any issues? Yes, but why take the chance? THis "test" was a short cut way back in the 60's left over from post war vehicles with generators.

Loose power connections have shorted out more electrical components than anything else in history. (An assumption on my part. No actual data collected...)

Regarding a vehicle that dies when the battery is disconnected: A good electrical system SHOULD have kept it running. But who knows what failed at the same time as the disconnect? The Regulator? The main module? The ground wire? Who knows? Maybe the alternator/wiring was DEAD/shorted before the disconnect.....

You begin your post with Never in all caps and bold type and then you say it can be done without issues. Then you say it has ruined more electrical components than anything else in history followed by that is an assumption. Confusing again.