No Start!

[Nisfro98]

A few weeks ago my car would not start all of a sudden. No crank or even click. everything else operated normally; lights, cluster, radio, etc. Pulled the codes and pointed to CAS (Car Access System). Mileage is 65k with Alpine tune and 6MT

A0B4/present CAS: Engine Start, starter operation
A0C1/not present CAS: Output, terminal 50
A0C2/not present CAS: Output, terminal 50 RS

My research pointed to 3 main culprits with this terminal 50 error, 2 of them being very unlikely; bad starter, bad CAS module, bad clutch switch with CAS and clutch switch being very unlikely. From what I read terminal 50 is the 12v post on the starter solenoid. With 65k miles I was a little skeptical the starter could have died but I ordered a new one. With that one in transit I started the tear down and removed the old starter. Rec'd the new start and decided to bench test both hooked up to my DD. Both engaged no problem. So I thought well maybe the m3 battery. The battery light did come while I was trying numerous times to start the car so I put in on trickle charger. It was reading at 12.2v but still I've seen some funky things with batteries so I decided to bench test using the m3 battery and both engaged no issue. The old started is original Bosch and the new one is SEG ordered from fcpeuro, not reman. so I decide to start putting it back together with the SEG hoping somehow it would start. No start. same error codes.

could it actually be the CAS or could it be a relay switch? Where is this part located and if it is the switch would there be a different terminal number in the error?
Relay Switch

Clutch switch? I havent looking into this yet but would this also have a different terminal number?

Also read quite a few comments on checking ground connections. Need some help locating them. I know one is near the exhaust header accessible from under the car. There are two on the driver side valve cover and one that's connected to the solenoid (which I believe connects to the alienator?) . Where do these connect to on the other end?

[omgzirra_exe]

12.2V is too low for the battery lol. literally replace it.

[Helmsman]

Originally Posted by omgzirra_exe

12.2V is too low for the battery lol. literally replace it.

My car easily starts when battery is creeping even belowe 12V. In fact even a brand new/charged battery doesn't hold more than 12.3-12.4V after car is woken up, so I wouldn't view the battery to be an issue here.

[Nisfro98]

The battery is from 2017. I experienced this with my dd. Car would not turnover even tho the battery was over 12v. Bought a new one and started right up. I wonder if the same thing is happening here.

I'm getting 12v to the solenoid. So it's either ground or cable to the solenoid switch. Where does the ground lead? To the alteralnator?

[omgzirra_exe]

Originally Posted by Nisfro98

The battery is from 2017. I experienced this with my dd. Car would not turnover even tho the battery was over 12v. Bought a new one and started right up. I wonder if the same thing is happening here.

I'm getting 12v to the solenoid. So it's either ground or cable to the solenoid switch. Where does the ground lead? To the alteralnator?

but I also believe it's a failing starter solenoid. if putting your car on a jumper cables and it doesn't start, before you decide to replace the battery.

Originally Posted by Helmsman

My car easily starts when battery is creeping even belowe 12V. In fact even a brand new/charged battery doesn't hold more than 12.3-12.4V after car is woken up, so I wouldn't view the battery to be an issue here.

yes it can start, but it is still to low of a voltage depending on where you live. when my battery was at 12.2v it would give me the warning every time i shut my car down and sat in it for 5 minute as it would have small features still turned on.

and when i was cleaning my interior, the battery drained lol.

[Nisfro98]

Its not the starter/solenoid. I tested both before I installed the new one. Also installed a new battery. Thats not it either.

[yardbro]

Originally Posted by Nisfro98

Its not the starter/solenoid. I tested both before I installed the new one. Also installed a new battery. Thats not it either.

If the CAS is showing a terminal 50 fault, it most likely is not going to be a clutch or neutral switch issue. What this is telling us is that the CAS module "thinks" it's telling the starter to engage, but the engine did not start. This would not happen if it was missing a neutral or clutch switch signal.

Since you have bench tested the starter and solenoid and know it's not faulty, start with checking that you have block ground (thats where the starter gets ground from). I doubt you're missing block ground in this case as you would have many more errors than just your starter not working.

The last thing to check is the terminal 50 wire that plugs into the solenoid, X6510 in the diagram below. Unplug it from the starter and use a test light to see if it's getting 12v when you press the start button. If there isnt 12v on that wire during start command, you either have a break in that wire somewhere, or the driver for that circuit in your CAS module is fried.

[Honda]

This is a typical starter problem. Bench testing the starter doesn't mean it is good. Replace the starter and report back

[Bmwdoubles_]

If you’re over 100k it’s time to replace the starter. Battery or not. Mine ended up being the starter. It would not crank and repeatedly pressing the button for several minutes did nothing and then suddenly on some lucky press of the button it started. Replaced the starter now it starts the car like it was new.


Super pita install. The two bolts on the side to release the starter were major pain. Worth the effort though instead of paying the dealer a million dollars.

[OneSickM]

Originally Posted by Bmwdoubles_

If you’re over 100k it’s time to replace the starter. Battery or not. Mine ended up being the starter. It would not crank and repeatedly pressing the button for several minutes did nothing and then suddenly on some lucky press of the button it started. Replaced the starter now it starts the car like it was new.


Super pita install. The two bolts on the side to release the starter were major pain. Worth the effort though instead of paying the dealer a million dollars.

If you don't mind sharing what you did to remove the side bolts, that would help the community. I am going to tackle this next month and I am already prepared in my mind how painful it is for a DIY

[Bmwdoubles_]

Originally Posted by OneSickM

If you don't mind sharing what you did to remove the side bolts, that would help the community. I am going to tackle this next month and I am already prepared in my mind how painful it is for a DIY

I don’t remember what size of the torx and e-torx were. UPDATE: outter bolts are an e12 The center one is easy, I think that one was the e-Torx.

I did the two outer Torx ones first so that the center kept it hanging. And then on the install the center e-Torx one went in first. Use the thinnest possible ratcheting wrench and make sure the torx is fully seated in the bolt. That thing you don’t want to happen is to strip that thing. Honestly, if you can have a person seat the torx socket and hold it while you attach the wrench to the socket, that would be optimal. I did it alone, so the challenge was high. Bungee cord the main wiring harness.

Also, it takes a while for the bolt to come out because the bolt is kinda long so don’t remove the the Torx until the bolt is all the way released otherwise you’ll have to redo the Torx seating and go through the pain again.