E46 Fanatics Forum banner
Status
Not open for further replies.

No Start Guide

1M views 747 replies 222 participants last post by  Kolonel-Black-Fox 
#1 ·
If your car won't start, the fix can be as simple as replacing the battery, but there are many other potential causes and troubleshooting can be challenging. The following is an overview, intended to help with the diagnosis.

1. Low voltage
Bad battery
If the starter isn't cranking, or there is only a click, first check battery voltage with a digital multimeter (see photo in post 39), or using the OBC hidden functions (see info in post 37).
It needs to be at least 12V for the starter to be able to crank, while full battery voltage is close to 12.6V.
Faulty alternator
The battery may have died because the alternator isn't charging it.
To test the alternator, first start the car by charging the battery, by jump start, or push start. Measure battery voltage with the engine running, it should be close to 14V, or slightly over.
Bad connections
If the battery and alternator are OK, but voltage is low at the starter, there could be a loose, or corroded connection in the electrical system, causing a voltage drop. Check the ground strap under the engine on the passenger side and the battery terminals. The battery safety terminal (BST), located on the positive battery terminal, is designed to cut off power to the engine in case of an accident. If voltage is sufficient at the battery, but low at the underhood jumper terminals, there is a bad connection at the BST. (see photo in post 60)
Parasitic draw
If the engine runs fine when the battery is charged, or after a jump start, but the battery is dead by morning, there could be a short in the system draining the battery overnight. This is referred to as parasitic draw and on the E46 it is usually caused by a faulty final stage resistor (FSR) of the blower motor. Aftermarket equipment is another common source of parasitic draw.

2. Fuel related
Fuel pump
If the starter is cranking, but the engine isn't starting, the most likely issue is the fuel pump. There are a number of ways to verify.
  • listen for the pump to prime when key is turned to position #2
  • check for fuel at the fuel rail at the Schrader valve
  • measure the actual fuel pressure (or lack thereof) at the rail, it must be 50 PSI
  • spray starting fluid into the intake, if the engine stars briefly, fuel isn't reaching the engine.
You can also remove the fuel pump cover and whack the pump, this may get it going temporarily. This "method" can come in handy if you're far away from home.
Engine is flooded
The M54 engines flood easily if they are started and run for a short time, like moving from one parking spot to another. If the engine won't start shortly thereafter, the spark plugs might be saturated with fuel, preventing spark. No start at a later time may be due to loss of compression. See Section 6. for more info on that.
No gas in tank
If the engine stalls, or will not start when the gas is under ¼ tank, the fuel pump is weak and should be replaced. The gas tank has two lobes and a weak pump isn't able to transfer fuel from the other lobe. Fuel gauge maybe inaccurate, reading too high.
Bad gas
No start after the car was sitting for a long time. If your car runs rough and/or won't start right after filling up with gas, the fuel might be contaminated.
Fuel filter
A clogged, or restricted fuel filter usually causes engine performance problems, but it can also contribute to no/hard start.
Fuel pressure regulator
On the 325i/330i this is part of the fuel filter, so by replacing the filter, the FPR will also be renewed. On the 323i/328i it's separate from the filter. These rarely fail on the E46, but it's a possibility. No start due to no, or low fuel pressure can be caused by a defective fuel pressure regulator.

3. Starter
If battery voltage is sufficient at the starter's electrical connections and the starter is not cranking, it is most likely defective. Replacing the starter isn't easy, so make sure the diagnosis is correct before you undertake this task.
Suggestions for troubleshooting: remove the airbox and the intake boots to gain access to the starter. Measure voltage on two of the terminals on the starter solenoid. Terminal "B" should have constant battery voltage. Terminal "C" is energized by the ignition switch via EWS module when starting the engine. Remove the wire from this terminal, measure voltage on the wire with the key in start position.
Motor vehicle Coil Automotive fuel system Gas Auto part


If sufficient battery voltage is present at both terminals and the starter isn't cranking, it is defective. You can also test the starter by jumpering, or "hot wiring" it. This is done by applying direct voltage to some of the terminals. When voltage is applied to terminal "D", the starter motor should spin without cranking the engine. When voltage is applied to terminal "C", the starter should crank the engine. Make sure you have good engine to chassis ground. Sometimes there is a bad connection at the ground strap that is under the engine on the passenger side. The starter can also get stuck. If voltage is sufficient, but the starter only clicks, this may be the case. Tap the starter while a helper attempts to crank the engine. If it is stuck, this may get it going.

4. Switches and sensors
Ignition switch
If there is no power at terminal "C" on the starter with the key in the start position, there is either an EWS problem, or a bad ignition switch. A faulty ignition switch can cause either a no crank/no start, or crank/no start condition. Intermittent no start, or strange electrical symptoms are also typical signs of a failing ignition switch. Wiggle the key as you start the car, that sometimes works if the switch is bad.
Cranks but no start
Check battery voltage at fuse 29 while starting. This is the ignition switch input to the DME. (see photo in post 60). Check battery voltage at pin 15 on the coil harness with the ignition on. (see photo in post 61). Warning lights going off on the dash randomly, or suddenly while cranking is an indication of a faulty ignition switch.
No crank
Check battery voltage on the black/blue wire at the ignition switch connector with the key in the start position. This wire supplies voltage to terminal "C" on the starter via the EWS module while starting. No voltage in any of the tests indicates a defective switch.
Clutch switch
A defective clutch switch, (or not pressing the clutch pedal far enough) will prevent starting. If battery voltage is OK and starter doesn't crank, this is one of the possible issues. To test the switch, bypass it by inserting a jumper wire in its connector. (wires violet/yellow and black/blue) Switch designs vary throughout the years.
Auto (neutral) safety switch
This is the equivalent of the clutch switch on an automatic, it allows the engine to start only in "P" and "N".
The gear selector switch, located on the side of the transmission performs this function.
Move the shifter back and forth a few times before starting, this may enable start, if the switch is faulty.
Crank position sensor
The DME needs the signal from this sensor to fire the plugs. A faulty crank sensor usually throws a code, making diagnosis simple. If there is no code stored for this sensor, but no spark is suspected, check for spark. See post 62 for info on how to check for spark. If there is spark, the crank sensor must be doing it's job. If there is no spark and no crank sensor code, look at the tachometer while cranking. If the sensor works, the needle should read about 200 rpm.
Camshaft position sensor
A defective cam sensor most often results in driveability problems, like stalling, loss of power and rough running, but it can also prevent the engine from starting. This usually causes CEL, too.

5. Fuses, relays and modules
Immobilizer (EWS)
A faulty EWS module, a key that is not coded to the module, or damaged will prevent the engine from starting. There won't be any power at terminal "C" on the starter solenoid, resulting in a no crank condition. If you hear a beep with the key in the ignition and the driver's door open, the EWS is recognizing the key. Trying to start the car with a second key is another simple way of ruling out a no start due to a non working key. A scan with a BMW specific scanner is necessary to detect EWS faults. If your car is equipped with an additional aftermarket alarm system, make sure it is disarmed.
Fuses
E-box fuse pack

Under the hood on the driver's side where the DME and other electronic components are located, there is a fuse pack, containing 5 fuses. These are related to engine management. Fuse #3 sends power to both fuel pump relay and the crank sensor. (see photo in post 142)
Main fuse panel
Check fuses 9, 22, 27, 29, 30 (ignition switch), 54 (fuel pump), and 14, 49, 67 (EWS). Inspect all fuses in the glove compartment if you're dealing with a hard to diagnose no start problem. Check the high amp fuses above main fuse panel (fuseable links). There is an 80 amp for the DME and DME main relay, and a 50 amp fuse for the ignition switch. Check the harness fuse: behind the carpeting on the passenger side shock tower there is a large fuse. The cable here supplies the relay panel, so if this fuse is blown, almost everything will be out.
DME Relay
Unlike the older models, this isn't problematic on the E46. Test this relay if there is no battery voltage at the E-box fuses. See post 408 for info on trouble shooting!
Electronic Control Unit (DME)
DME failure is also not common, but possible. A scan with a BMW specific scanner usually reveals if the unit is faulty. There may be no codes stored. If there is no spark, or injector signal and all DME inputs and wiring are OK, the DME needs replacing.
Fuel pump relay
No power at the fuel pump may be caused by a bad fuel pump relay. When checking for power at the pump, the engine needs to be cranked. A simple test for the fuel pump relay is to swap it with the horn relay, they are identical. Additional electrical tests can be done by jumpering terminals at the relay board. If the pump runs with the terminals jumpered, but not with the relay in place, the relay is defective.

6. Mechanical issues
No compression
An engine needs spark, fuel and compression to run. If there is both spark and fuel and your car won't start, test engine compression. At times a condition called cylinder wash down occurs. If the engine started and run for a short time, or when an engine is cranked without starting, a lot of fuel is dumped into the cylinders. This can wash the oil off the cylinder walls and lead to loss of compression. Pour some oil in each cylinder, this will restore compression.
Camshaft timing
The timing chain assembly is reliable on the 6 cylinder engines, but can be problematic on the 4 cylinders models.
Engine seized
An internal mechanical failure can cause the engine to lock up. Try to turn the crankshaft manually to see if the engine is frozen.
Hydrolock
The crankshaft can not rotate due to liquid in the combustion chamber. This can be fuel, coolant, or oil, caused by a leaking fuel injector, head gasket, or a malfunctioning CCV system. Remove spark plugs and crank the engine if this is suspected.
Vacuum leak
Vacuum leaks usually cause rough running, or misfires, but a large vacuum leak can prevent starting. If your car won't start after working around the intake, this is the most likely problem. In this case the engine may start up momentarily, but stalls immediately.
 
See less See more
1
#130 ·
Trans Failsafe PROG disable starter?

Firstly, thanks @Iszlszx for the best no-start tutorial I've come across.
Is it possible, that, similar to P/N block starter motor error experienced by @jcieslik , no start no crank could be caused by multiple attempts to crank while in TRANS FAILSAFE PROG ?
I've not been able to crank for nearly one month now, which is my own doing, when rebuilding the fuel and emission systems, as well as replacing spark plugs and valve cover gaskets.

It didn't help that I tried to replace the battery on my original FOB remote and reprogram it for use unsuccessfully. My master key (purchased from Crevier BMW before unsuccessful attempt at reprogramming FOB remote) still turns the ignition to position 2 and I can run the radio, cluster tests, etc.
Also I should note that I purchased a TCM from an identical model, but the was starting at the time with the original TCM, but not the replacement TCM.

Will get the multimeter out now that this thread has shown how to test starter.
Thanks folks:)
 
#131 ·
Update! It starts!

Thank you very much, Iszlszx for the info and help. I could not have done it without this trouble shooting guide.

I read a lot about how to change the starter and was pretty confident that I could change it easily and the problem was there. It ended up taking me exactly 3 hours from start to finish. By far the hardest part was using the factory car jack to get the car high enough to put jack stands under it. Damn thing broke on me when I was letting it down. Luckily I was all clear and only suffered a small scratch on my rocker panel.

All in all, the starter swap is not as hard as it seems. Just a lot of tight spaces.

Thanks again. If you're ever in Chattanooga, TN, I'll buy you a beer or 10. Cheers!
 
#140 ·
Yesterday I drove approx 20 Kms and then the fuse blew. Replaced it drove a few more Kms and it blew again. It did that three times. Then this morning I drove and she seems to be okay. No wiring has been touched alarm is standard BMW. The crank sensor was changed last week but the car was fine for the entire week till yesterday. And I did quite a bit of mileage in the last week.
 
#141 ·
http://forum.e46fanatics.com/showthread.php?t=865516

So, middle fuse in E-box...#3--20amp

Controls:

AC compressor clutch relay
Camshaft position sensor
Crankshaft " "
DME Main relay
Fuel pump relay (hmmm?)
leakage diagnosis pump (fuel tank)
MAF
SAP relay
Thermostat

Man, that's a lot of stuff for this one fuse...but all relays or sensors...no real 'part'!

Anyway, some common items for you with both the DME and SAP and fuel pump relay

Not sure what it all means for you, but hth

BTW, my source is Bentley...610-3 (awesome resource!)
Being that my car has simultaneously thrown error codes p0101, p1622 and p1397 I found dmax's quote on the thread linked above important to be placed here since this thread talks about issues with no starts, and this one fuse controls so many things.

Great thread btw op
 
#144 · (Edited)
Thanks to this site and this thread. Recently bought a 2001 325xi with 117,000 miles for a solid price. Had key issues right off the bat and eventually the car would not even start. Everything would light up but car would not turnover and remote functions of key also quit. I proceeded to use the key manually and the drivers door lock cylinder broke!!!!! My lord, what have I gotten myself into? I joined this site and started researching for answers and boy did I find them. Door cylinder repaired by me but still had the no start problem. I read this entire thread and started the process of elimination. All along, I was suspicious that the transponder chip in the key may have been the culprit (battery was confirmed good in key). Since I needed a new key anyway due to remote buttons broken, I went ahead and ordered one from a dealer for $178.00 and had it in my hands the next day. Dealership personnel advised that the key itself would not be causing the no start issue. Well, when I got home, I put it in the ignition and it started right up. Moral of the story, the key transponder was bad and the dealership was wrong. Thought I would add this info to this thread and hopefully it will help someone else. Heaven knows, this thread and site has helped me. Kudos to the OP......
 
#146 ·
No Crank/Start on my E46 Yesterday.

Checked Voltage Up Front Under Hood 12.82V
Checked Battery In Back 12.90V - Battery is 1 month old Bosch
Checked Fuse 29, While Wife Turned Key - 12.42 Volts

Can you checked the starter wires from below or is the only way to check them via removing everything up top?

Joe
 
#148 ·
I have tried the second key, granted it doesn't unlock the doors because the battery is dead but it has started the car in the past.

I fired up PASoft 1.4 and confirmed the keys were being read by the EWS and the EWS as green and ready for start just no crank.

I'm starting to think the slow cranking which I thought was a old battery may have been the starter going out.

As far as I know when I need other work such as CCV and Cooling system refresh the starter looked original and just hit 200,007 miles.

I just don't want to tear into it if it's the ignition switch or something easier! I bought a NEW Bosch starter on Amazon yesterday that will arrive today and I'm deciding how easy this will be able to tackle from above.

I might just cough up the dough to have someone do it. I heard book time is 2.5 hours?

Thoughts?

Joe
 
#151 ·
E46 330ci Crank no start

Had an intermittent issue of crank no start when engine was left overnight which progressively occurred more often.(winter time here temperature from 0 deg c to 12 deg C).
You would have to recycle the ignition switch many times to get it to prime then the engine would start and run perfectly.
Had a pretty good read of all the BMW forums to help resolve.
Tested power at fuel pump on connector on "prime mode" and got 12.2 to 12.3V....so replaced fuel pump...although I had tested pump with standalone battery supply and it ran....still suggested pump might be faulty.
Swapped out relays and fuses , new ignition switch, replaced filter/regulator, new DME relay.
Ended up being resistance within the plug female connector at the fuel pump connection itself, it appeared to be as new condition i.e. clean and dry.
I would get a voltage signal here but there was enough resistance to stop the pump priming and therefore starting.
Simply gave it a clean out with a small drill bit and all fixed.
When you turn ignition on the pump primes and runs to ensure fuel pressure at start up.
Had not seen this mentioned as an issue anywhere on the forums so it might be helpful to someone else.
I have learnt a fair amount about the starting systems /updated my fuel pump, which is a positive and replaced the fuel filter which by the dirt that came out of it was worthwhile.
 
Status
Not open for further replies.
You have insufficient privileges to reply here.
Top