Battery died, replaced it, still no start

[Thoglan]

UPDATE:

Diagnosed it to be a failed steering angle sensor thanks to the good ol' 50s kid lol.

https://www.youtube.com/watch?v=Ci6lrAUU7ms

No voltage at pin 8 on the OBD port until I unplug the steering angle sensor. And with the way these are wired if the steering angle sensor fails then communication with pretty much all the chassis modules is cut off as the video explains. Bittersweet since now I know what the issue is and it wasn't DSC. Downside being it's a total bitch to replace...

[sapote]

With the new battery in the starter clicks and turns over maybe once then nothing. No start. Lights are still present on the dash.

Any suggestions where to go from here?

How does a bad steering angle sensor cause the starter to click not able to crank?
I would think you have 2 separate problems: a bad sensor took out the Canbus, and a starter/battery issue.

[Thoglan]

How does a bad steering angle sensor cause the starter to click not able to crank?
I would think you have 2 separate problems: a bad sensor took out the Canbus, and a starter/battery issue.

That was just low voltage on the battery, once I replaced the battery and charged the new one it starts fine now. Although I haven't started it many times or driven it much since. My guess is the low voltage or the short with the battery is what killed the angle sensor.

[AWE46M3]

Thoglan - just watched the linked Youtube video. That repair looks like it sucks - sorry to hear that man. Thanks for posting the update - I am sure this will be helpful to someone else as all of our cars are nearing the age where these random sensors crap out.

[bigjae46]

That was just low voltage on the battery, once I replaced the battery and charged the new one it starts fine now. Although I haven't started it many times or driven it much since. My guess is the low voltage or the short with the battery is what killed the angle sensor.

If I had to guess, it was a bad SZL that killed your battery. Then not uncommon to have to charge a new battery. It might have sat for awhile.

FYI…the battery cable runs to the starter and a buss on the back of the fuse box. There are larger fuses on the buss which feeds the blade type fuses.

Check voltage AND resistance. If you have 12v at the jump post the next step is to check resistance. 12v with high resistance can cause a no-start. The safety terminal could have partially activated or there could be a break in the wire. Checking resistance can save you from an electrical fire as well.

I typically check resistance first.

[Thoglan]

I messed around with the car for a bit earlier today. The plot thickens...
The car was very slow to start, almost thought it wouldn't, just barely cranked over and started. So I think there is still some kind of voltage drain or bad ground issue. I haven't checked the engine chassis ground yet since I've been busy all week but it's bothering me more and more now so I will check it asap.
The weird part is, I wanted to scan the steering angle sensor in INPA expected to get no data from it if it was bad, but all the values updated and were accurate in real time. So I checked the voltage at pin 8 again and there was voltage, so it seems that is actually not the issue and I was measuring it wrong.

I'm thinking I was right initially in that the ABS unit itself is dead. When I unplugged the unit altogether the errors did not change at all, on the dash or in INPA. I also came across this thread: https://www.e46fanatics.com/threads/...0-dsc.1293248/ where a guy has a similar issue and similar codes (132,135,139, although he has a couple additional codes as well) where there is no access to the DSC module, and he ended up having to replace it to read the codes which showed a yaw sensor out as well. I think I'm going to have to bite the bullet and grab a second hand MK20 unit.
Additionally, would a dead ABS unit cause a power draw causing the slow start?

Check voltage AND resistance. If you have 12v at the jump post the next step is to check resistance. 12v with high resistance can cause a no-start. The safety terminal could have partially activated or there could be a break in the wire. Checking resistance can save you from an electrical fire as well.

I typically check resistance first.

I'm going to embarrass myself here but I don't actually know how lol. My knowledge when it comes to electricals is not great. I have a multimeter but where and what am I measuring the resistance from? What numbers should it be?

[bigjae46]

I messed around with the car for a bit earlier today. The plot thickens...
The car was very slow to start, almost thought it wouldn't, just barely cranked over and started. So I think there is still some kind of voltage drain or bad ground issue. I haven't checked the engine chassis ground yet since I've been busy all week but it's bothering me more and more now so I will check it asap.
The weird part is, I wanted to scan the steering angle sensor in INPA expected to get no data from it if it was bad, but all the values updated and were accurate in real time. So I checked the voltage at pin 8 again and there was voltage, so it seems that is actually not the issue and I was measuring it wrong.

I'm thinking I was right initially in that the ABS unit itself is dead. When I unplugged the unit altogether the errors did not change at all, on the dash or in INPA. I also came across this thread: https://www.e46fanatics.com/threads/...0-dsc.1293248/ where a guy has a similar issue and similar codes (132,135,139, although he has a couple additional codes as well) where there is no access to the DSC module, and he ended up having to replace it to read the codes which showed a yaw sensor out as well. I think I'm going to have to bite the bullet and grab a second hand MK20 unit.
Additionally, would a dead ABS unit cause a power draw causing the slow start?



I'm going to embarrass myself here but I don't actually know how lol. My knowledge when it comes to electricals is not great. I have a multimeter but where and what am I measuring the resistance from? What numbers should it be?

To measure resistance of the battery cable, remove the cable from the battery. One probe on the jump post and one on the cable terminal. You want 1-100 ohm range.

You should get a low reading around .01 ohms. If you get a higher reading over 1 ohm or no reading then there is an issue with a battery cable. Not unheard of to have a
bad cable…there is a repair kit. The battery safety terminal sometimes goes bad which causes a similar issue.

[Thoglan]

To measure resistance of the battery cable, remove the cable from the battery. One probe on the jump post and one on the cable terminal. You want 1-100 ohm range.

You should get a low reading around .01 ohms. If you get a higher reading over 1 ohm or no reading then there is an issue with a battery cable. Not unheard of to have a
bad cable…there is a repair kit. The battery safety terminal sometimes goes bad which causes a similar issue.

Legend, thanks will measure today.

[Thoglan]

Measured resistance as bigjae46 suggested and resistance was just over 1 ohm so the battery cable appears to be all good. Hopefully I'll have time to check the ground in the next day or so. Also have a line on a second hand MK20 for a good price so I think I'll grab that and chuck it in.

[sapote]

Measured resistance as bigjae46 suggested and resistance was just over 1 ohm so the battery cable appears to be all good. Hopefully I'll have time to check the ground in the next day or so. Also have a line on a second hand MK20 for a good price so I think I'll grab that and chuck it in.

The batt cable resistance measured from the jumper post to the batt cable terminal cannot more than 1 ohm; should be less than 1 ohm. But first, touch both voltmeter leads together and see what is the resistance value for this short circuit, and this is your ideal "zero ohm" offset value of the voltmeter, then subtract this offset to the real measured valve of the long batt cable. Btw, don't measure at the jumper post nut, but on the terminal of the black cable connected to the starter, and the other end is on the batt cable terminal. This means you need to make a long lead the length of the car.

It can't be 1 ohm or higher, because the starter draws more than 50A during cranking, then the voltage drop on the long cable is V = I*R = 50A * 1 ohm = 50v; well, it's impossible because a 12v batt can't drop 50v on the cable.

[Thoglan]

The batt cable resistance measured from the jumper post to the batt cable terminal cannot more than 1 ohm; should be less than 1 ohm. But first, touch both voltmeter leads together and see what is the resistance value for this short circuit, and this is your idea "zero ohm" offset value of the voltmeter, then subtract this offset to the real measured valve of the long batt cable. Btw, don't measure at the jumper post nut, but on the terminal of the black cable connected to the starter, and the other end is on the batt cable terminal. This means you need to make a long lead the length of the car.

It can't be 1 ohm or higher, because the starter draws more than 50A during cranking, then the voltage drop on the long cable is V = I*R = 50A * 1 ohm = 50v; well, it's impossible because a 12v batt can't drop 50v on the cable.

You're right I must have misread Bigjae's comment. I actually just re-measured the resistance from the negative lead to the jump post the way you said the the reading was 174.5ohms. False readings (caused by user error) seem to be a theme here lol.

So this would suggest the battery cable is bad? Presumably I'll need this: https://www.fcpeuro.com/products/bmw...12#description

[heinzboehmer]

So this would suggest the battery cable is bad? Presumably I'll need this: https://www.fcpeuro.com/products/bmw...12#description

That's the BST repair kit. Looks like wire from battery to firewall is 61122695530. Firewall to positive post in engine bay is 61136910539.

Past that there's the alternator wire too. You can isolate which section is bad by measuring each in isolation.

Edit: Just looked up prices of all these things. Funny how the entire wire is significantly cheaper than the patch in repair kit.

[Thoglan]

That's the BST repair kit. Looks like wire from battery to firewall is 61122695530. Firewall to positive post in engine bay is 61136910539.

Past that there's the alternator wire too. You can isolate which section is bad by measuring each in isolation.

Edit: Just looked up prices of all these things. Funny how the entire wire is significantly cheaper than the patch in repair kit.

I also just retested cause I didn't trust myself and realised I had the multimeter hooked up to the negative lead. The actual reading from positive lead to jump post is 0.3 ohms, and the resistance from the multimeter is about 0.2 so the battery cable is fine. Lol, electrical stuff is definitely not my strong suit.

Tried to start the car yesterday with a fully charged battery reading 13.1v across the terminals and it didn't even start just cranked over a couple times. Voltage at the jump post fell below 8v while cranking so I think there has to be a bad ground somewhere.

[sapote]

Voltage at the jump post fell below 8v while cranking so I think there has to be a bad ground somewhere..

Where did you touch the voltmeter black lead? should be on the engine metal and not the chassis. Compare the reading (while cranking) when touching the black lead to chassis and to engine metal and if they are the same then the engine ground strap is good.

[0-60inM3]

I am having similar issues after I accidentally dropped a wrench and caused a short, I lost all communication with the OBDII, dash went dark, no tack or speedo, light flashing above mirror, sudden no start, windows not dropping for close, alarm going off while driving the car, alarm while parked with car unlocked and other electrical issues. The most concerning is the OBDII port not communicating with any BMW software, but will communicate with the ECU. Thank you to those that have posted, the info is intelligent and helpful.