Car takes 5 mins to start - what's the issue?
Discussion
My E60 M5 has been developing an annoying issue recently, actually it's been going on for a few months but has got worse I think.
If I don't use the car for more than a day or two, turning the ignition key doesn't do anything and the car doesn't try to start. During this time the yellow engine warning light is illuminated. After I leave it for 5 mins the car starts up and drives just fine and there's no warning lights or anything.
I've taken it to a main stealer aleady and paid them £100 for telling me "I'm not driving the car enough". Which is true most of the time since it's not a daily car but the same thing happens no matter how long/short my previous drive was.
So any ideas? Battery, alternator, just a sensor, or something more substantial?
If I don't use the car for more than a day or two, turning the ignition key doesn't do anything and the car doesn't try to start. During this time the yellow engine warning light is illuminated. After I leave it for 5 mins the car starts up and drives just fine and there's no warning lights or anything.
I've taken it to a main stealer aleady and paid them £100 for telling me "I'm not driving the car enough". Which is true most of the time since it's not a daily car but the same thing happens no matter how long/short my previous drive was.
So any ideas? Battery, alternator, just a sensor, or something more substantial?
How old is the battery? If more than 5/6 years old and you're not using the car much it could be that. See if you can borrow a 'good' battery from someone and fit it to the car after its not been driven for several days and see if it starts. If it does, its the battery, if it doesn't, at least you know its not a battery issue probably.
Battery hasn't been replaced in 4 years at least, but I don't have access to another battery to test. Even if I did I'm under the impression that the car needs to be re-coded to recognise a new battery.
What's strange is that it never fails to start, seems like the car just needs a few mins to wake up.
What's strange is that it never fails to start, seems like the car just needs a few mins to wake up.
There have been a few of us exeriencing this or something similar lately. My car does it on occasion, but has behaved well for the last month. You can have any auto parts store test the battery, just remove and take it in on their test unit and it will perform load testing.
If the battery tests ok, that's where it gets more complicated.
There is a Car Access Module (CAS module) located in the drivers side footwell. This module receives the signal from the key receptacle antenna ring that a proper code has been presented and then matches that code to one stored in the CAS module and one in the DME.
- If the code presented to the CAS module matches what is expected, the CAS module actuates a relay (known in BMW tech docs as "Terminal 50") which supplies power to the starter solenoid.
- The key's code is also passed from the CAS to the DME and if it matches what the DME expects, the DME passes a "start permissive" signal to allow engine startup.
I began to suspect the relay inside the CAS module on my car was becoming worn and would require replacement. So, when the key was passing the proper codes, the CAS and DME were trying to do their job, but pitting/oxidization/etc on the relay contacts was causing excessive voltage drop and preventing sufficient current to be delivered to the starter solenoid. I could very definitely hear the "click" of the solenoid every time, but the engine never turned over. However, this has now gone away and I haven't had a start failure in 6 weeks. The only way to know for certain would be to replace the CAS module since the relay inside isn't replaceable (yet...working on that) and unfortunately the CAS and DME are matched to each other and have to be replaced in pairs. That makes an expensive "guess" fix.
Another possibility is that the CAS and DME have become out of sync with each other. When the key presents the code, both the CAS and DME look to see if it's the code that is expected. With each successful start, both the CAS and DME increment their expected code such that a different code is expected next time, but the two modules remain in sync with each other. At times, they can become out of sync and while the key sends the code that the DME expects, it's not the one the CAS expects (or vice versa). There is a software function in ISTA/D which allows resync of the CAS to the DME.
The only way to really move forward though is with the actual 4 digit alphanumeric error codes stored in the DME or CAS module. Have the car's error memory (all modules) read out by a dealership or indy post them here...happy to look them up for you.
Mine never really stored a code in any of its failed starts, but recently I had an SMG fault that caused me to pull the codes and I found a "Terminal 50 voltage low" error which helps confirm my suspicion of the CAS relay.
If the battery tests ok, that's where it gets more complicated.
There is a Car Access Module (CAS module) located in the drivers side footwell. This module receives the signal from the key receptacle antenna ring that a proper code has been presented and then matches that code to one stored in the CAS module and one in the DME.
- If the code presented to the CAS module matches what is expected, the CAS module actuates a relay (known in BMW tech docs as "Terminal 50") which supplies power to the starter solenoid.
- The key's code is also passed from the CAS to the DME and if it matches what the DME expects, the DME passes a "start permissive" signal to allow engine startup.
I began to suspect the relay inside the CAS module on my car was becoming worn and would require replacement. So, when the key was passing the proper codes, the CAS and DME were trying to do their job, but pitting/oxidization/etc on the relay contacts was causing excessive voltage drop and preventing sufficient current to be delivered to the starter solenoid. I could very definitely hear the "click" of the solenoid every time, but the engine never turned over. However, this has now gone away and I haven't had a start failure in 6 weeks. The only way to know for certain would be to replace the CAS module since the relay inside isn't replaceable (yet...working on that) and unfortunately the CAS and DME are matched to each other and have to be replaced in pairs. That makes an expensive "guess" fix.
Another possibility is that the CAS and DME have become out of sync with each other. When the key presents the code, both the CAS and DME look to see if it's the code that is expected. With each successful start, both the CAS and DME increment their expected code such that a different code is expected next time, but the two modules remain in sync with each other. At times, they can become out of sync and while the key sends the code that the DME expects, it's not the one the CAS expects (or vice versa). There is a software function in ISTA/D which allows resync of the CAS to the DME.
The only way to really move forward though is with the actual 4 digit alphanumeric error codes stored in the DME or CAS module. Have the car's error memory (all modules) read out by a dealership or indy post them here...happy to look them up for you.
Mine never really stored a code in any of its failed starts, but recently I had an SMG fault that caused me to pull the codes and I found a "Terminal 50 voltage low" error which helps confirm my suspicion of the CAS relay.
I'm another sufferer of the same problem, battery less than 6 months old so don't believe it to be part of the problem.
Very interesting detail in the above post. I've found the odd occasion when it does happen if I just lock the car from the remote key fob whilst in the drivers seat, give a few seconds then unlock she normally fires up straight away.
I was thinking of a worn key barrel but it's happened on either set of keys and as mentioned it only happens if it's been several days since I've driven her.
OP if you resolve it, please post the answer!
Very interesting detail in the above post. I've found the odd occasion when it does happen if I just lock the car from the remote key fob whilst in the drivers seat, give a few seconds then unlock she normally fires up straight away.
I was thinking of a worn key barrel but it's happened on either set of keys and as mentioned it only happens if it's been several days since I've driven her.
OP if you resolve it, please post the answer!
Thanks jcolley, that's great info. I'm booked in for a service in a couple of weeks and if it doesn't get resolved by then I'll tell them to look at that.
Session8 said:
I've found the odd occasion when it does happen if I just lock the car from the remote key fob whilst in the drivers seat, give a few seconds then unlock she normally fires up straight away.
I was thinking of a worn key barrel but it's happened on either set of keys and as mentioned it only happens if it's been several days since I've driven her.
Also good suggestions, I've never used the second key so will give that a go.I was thinking of a worn key barrel but it's happened on either set of keys and as mentioned it only happens if it's been several days since I've driven her.
Thought I'd update - car has been with BMW for a couple of weeks and they're recommending a new battery (current one is 9 years old), apparently everything else looks ok.
What's annoying is that it's not covered under warranty and they want me to fork out for a new battery before testing it again...
What's annoying is that it's not covered under warranty and they want me to fork out for a new battery before testing it again...
I'm going to take a guess and say that the battery or capacitor in the key fob is not doing too well, and putting it into the ignition charges it up a little. Once there's a bit of charge in the key fob, then the car can read the chip inside it and authorise the key and then proceed to allowing the car to be started.
I'm sure you'll find something if you do a search for BMW EWS (it's probably version 3 on your car).
I'm sure you'll find something if you do a search for BMW EWS (it's probably version 3 on your car).
Ok so quite a few months later the issue came back... after putting a new battery in it was fine all throughout summer but during the recent cold spell it started acting up again.
What's weird is that it appears to be temperature dependant (i.e. gets worse as it gets colder) and perversely, it gets worse if I've taken it on long drives rather than short ones.
Anyway I got the fault codes read out. Of course Sod's law meant that they could not replicate the issue...
What's weird is that it appears to be temperature dependant (i.e. gets worse as it gets colder) and perversely, it gets worse if I've taken it on long drives rather than short ones.
Anyway I got the fault codes read out. Of course Sod's law meant that they could not replicate the issue...
Shaoxter said:
Ok so quite a few months later the issue came back... after putting a new battery in it was fine all throughout summer but during the recent cold spell it started acting up again.
What's weird is that it appears to be temperature dependant (i.e. gets worse as it gets colder) and perversely, it gets worse if I've taken it on long drives rather than short ones.
Anyway I got the fault codes read out. Of course Sod's law meant that they could not replicate the issue...
A0C2 is the key here.What's weird is that it appears to be temperature dependant (i.e. gets worse as it gets colder) and perversely, it gets worse if I've taken it on long drives rather than short ones.
Anyway I got the fault codes read out. Of course Sod's law meant that they could not replicate the issue...
This is the CAS module monitoring the output of the relay which feeds the starter solenoid. A0C2 means that the current draw to the solenoid was below a minimum spec.
The best place to start is all the positive cable (plastic coated) nuts being tight. Start on the jump star point under the hood, make sure it's tight. Then go for the one next to the bank 2 ionic control module. After that there's one under the intake plenums on the bank 2 side of the wire harness which drops down to the starter solenoid. Make sure they are all nice and tight.
Also, double check both posts on the battery are tight.
I wouldn't think so. The E60 is the most finicky car I've ever seen for low voltage conditions. It's almost as if all the modules lack the hardware to gracefully handle low voltage conditions or software routines to report them properly. Instead, they generate all manner of random errors. CAN bus errors (your DSC module) are usually a good indicator. Unless something has physically damaged a twisted pair of wires for the CAN bus, voltage is usually the cause.
The SZL module has an amazingly high level of integration with every other module and cars behave very strangely when it isn't working proper whether due to voltage or whatever. Just last week I tested a CAS and DME I repaired in my car and the whole car went crazy. I put my DME and CAS back in and none of the errors cleared. I ended up having to reprogram the DSC and SZL, recode them both with NCSExpert, and recalibrate the SZL and DSC before my power steering would work properly.
There are quite a few members on M5board who have had the same slow starting symptom you describe. One theory is that the relay inside of the CAS module which cuts out the signal to the starter solenoid may be failing with pitting on the contacts or similar. It's not replaceable and very small, so no one has confirmed that yet. It's difficult to pin down because it goes away for months at a time.
The SZL module has an amazingly high level of integration with every other module and cars behave very strangely when it isn't working proper whether due to voltage or whatever. Just last week I tested a CAS and DME I repaired in my car and the whole car went crazy. I put my DME and CAS back in and none of the errors cleared. I ended up having to reprogram the DSC and SZL, recode them both with NCSExpert, and recalibrate the SZL and DSC before my power steering would work properly.
There are quite a few members on M5board who have had the same slow starting symptom you describe. One theory is that the relay inside of the CAS module which cuts out the signal to the starter solenoid may be failing with pitting on the contacts or similar. It's not replaceable and very small, so no one has confirmed that yet. It's difficult to pin down because it goes away for months at a time.
I had an E60 535D which was fantastically reliable throughout the 2-3 years I owned it.
When I replaced the car I didn't sell it immediately and left it parked on my path for a good 6-8 weeks prior to selling it. The new owner had no end of trouble with the car (specifically the electrics and driver airbag sensors?) and ended up selling it sharpish believing I had sold him a duff car.
It appears E60's don't like being sat unused for extended periods, especially in colder weather.
When I replaced the car I didn't sell it immediately and left it parked on my path for a good 6-8 weeks prior to selling it. The new owner had no end of trouble with the car (specifically the electrics and driver airbag sensors?) and ended up selling it sharpish believing I had sold him a duff car.
It appears E60's don't like being sat unused for extended periods, especially in colder weather.
Ok so the garage is saying it's the CAS module, seems like you were right from the start jcolley (how on earth do you know so much about this??)
They didn't mention anything about swapping the DME as well though, apparently they can special order the CAS (requiring my V5 and ID etc.) and program it? Does £500 for that seem reasonable?
They didn't mention anything about swapping the DME as well though, apparently they can special order the CAS (requiring my V5 and ID etc.) and program it? Does £500 for that seem reasonable?
Gassing Station | M Power | Top of Page | What's New | My Stuff