seanjordan20

This is why I said disconnect the IBS to see if it solves the problem. If it does then you need a new IBS. If it doesnt then mark that off the list as a possible issue.

seanjordan20

A no start can be an IBS issue

seanjordan20

I had a no start issue 2 months ago and it ended up being that my modules were not align. I reset the modules and have had no issues. But you are saying that you can get it started at times so as long as it is starting at some point I have ruled that out

Stranger12

so no start is definitly ibs ?

how much are they and what is the down side of not having one ?

how does ibs cut the power to the ignition ?

seanjordan20

Your IBS controls smart charging. No it is not definitely the problem. It is process by elimination. Does the car need it no? It just supposedly makes the battery last longer by smart charging and cutting off electronics when you have issues to supply the computers enough power for troubleshooting. They cost around $200. Replacing it is not a priority. The priority is finding the root of your problems. Do a search what IBS does for the BMW. Then you make your decision.


The IBS is not needed so disconnect it to see if it is the problem. If it isn't plug it back in.

Stranger12

many thanks for this and yes it does make sense.

I am just trying to work out why ibs would cut start as some other posts have also suggested.

I know this may not be the issue but just curious if all it is doing is monitoring and change charge rate then how can it stop cranking !!

seanjordan20

Look at it as a computer. If your processor over heats it will shut off and you can not turn it back on until it cools down to prevent complete failure. The IBS is just that a safety measure. It is a module that scans the charging system. If it sees an issue it will prevent it from starting, deactivate some features to save battery for troubleshooting. That is the purpose of it. This is why I said unplug it to make sure that is not or part of the issue. It could be malfunctioning or it actually seeing something wrong with the charging system

Stranger12

Ok checked the voltage regulator as suggested by some forums on the next and below is the result

It was accessed from hidden menu 9. It was charging at 14.7 to 15 v which most people say my regulator is busted as it should be charging at 14.4

When i turned the heater on it dropped to 13.7 and then back up to 14.6 to 14.7 this time
Then also addedd full beam and it dropped once again and backup to 14.6ish and kept around there. Once i change accessories off it returned to 14.7 to 15

Battery vomltage was 12.6 and when cranked dropped as low as 8-9 and then backup

Is it my regulator? Easy job to change ?

jtbgonesailing

The charging system is controlled by the IBS system, which is both temperature and state of charge dependent. If your ambient temperatures are low, then you can expect charging voltages to be high.

The fact that your charging system is adjusting to increases and decreases in load ( amperage draw ) indicates that the IBS is working properly and signaling the voltage regulator to adjust accordingly.

With a ambient temperature of 68f, 20c, on a fully charged battery, I would expect a charging voltage of 14.0-14.4 DC. Remember the IBS is attached to the negative post of the battery and among other functions, it senses the ambient temperature of the battery. So for a 14.7-15.0v charging rate on a cold day, I would suggest is in order.

The PDF file I wanted to attach is not working today from BMW university.

Stranger12

many thanks. i went by what many people said and mentioning it must be under 14.4v regardless

so you think it could be ok ?