325i no crank

[fixit52]

325i AT
Car will not turn-over. Battery good... will check ground next. Interior lights come on, and everything seems to work but will not crank.
I checked the AT interlock switch on the shift lever in the console. Light that illuminates selected gear position does not light... bulb is good.

Tested AT interlock switch by:
Volt meter tested interlock switch input wire (Grn/Yel) to brown (ground) wire of the Bulb while turning on the ignition switch. No voltage. I also jumped the AT interlock switch - input to output wire... as predicted, no go.

Because the interior lights are on, and the AT interlock switch is also low voltage circuit, I would think there should be voltage present.... even if the ground on the car is not sufficient to power the starter.

According to the circuit diagram, the AT interlock switch input wire comes from the ignition switch, through a fuse (10 amp), and to the AT interlock switch.

Questions:
Does anyone know where the 10 amp fuse is located? I have not looked for it as yet.
I'm guessing the ignition switch is the source of the problem. Without taking off the steering column plastic, is there an easy way to check this? Can I jump the ignition switch someplace other than inside the steering column.
Any other common sources of "no crank" on 325i's. I'm ok with cars, but this is my first German brand... new to this car... my son just bought it.

Thanks a bunch

 

[mjbst111]

try banging on the starter with a hammer while someone turns the key. Also test the wires that go to the starter for voltage. Small one while the key is turned. The thick one should always have voltage.

Don't know how accessible the starter is on these cars though. Haven't had to touch mine yet.

 

[equate]

I am having the same problem, check your distributor cap and rotor, im in the process of replacing mine.

Try pushing it up a hill and pop starting it. This would rule the starter out if it wont start.

 

[fixit52]

I agree the starter is the obviuos place to start the search for the electrical problem. The reason I started at the Automatic Transmission interlock switch is the car had this problem before and I messed with this switch and it started... maybe not the actual cause and effect because it just started, and I never figured out why. This was a few months ago and it was cold then so I didn't pursue it any further. It's an intermittant problem, the worst to try to figure out.
I'll keep you posted.

 

[mjbst111]

i see, that makes sense... sorry i can't help out with the rest of your questions....

just to clarify, when i said hit the starter with a hammer, i mean tap it, well i can't explain how hard to hit it... just don't damage it! haha...

 

[nadroj]

try banging on the starter with a hammer while someone turns the key. Also test the wires that go to the starter for voltage. Small one while the key is turned. The thick one should always have voltage.

Don't know how accessible the starter is on these cars though. Haven't had to touch mine yet.

lol i tought you were kidding at first

 

[fixit52]

Had battery checked, it was low but ok. Charged battery. Fuse # 10 (7.5 amp) was bad. Changed fuse. Car cranked and started immediately. Battery light on dash was illuminated red and stayed on. In the original, I thoughtthe fuse was a 10 amp fuse, but it was fuse # 10 (7.5amp). It was the cause of the "no vlotage" at the AT interlock switch. So, it all makes sense that this was the cause of the "no crank" problem.

It ran ok for about 45 minutes... test drove ok.

Then the headlights went very dim... less than half brightness. I suspect the charging system is bad. I thought the battery would last longer than 45 minutes, but maybe I'm wrong... the car would still run, but less smoothly.

Questions:
1) process to check the alternator? I have volt / amp / ohm meter.
2) Common problems with the charging system? Has anyone had any similar problems, and what was the cause?

Any info would be helpful.
I saw a message on another web site about the alternator brushes worn, and how to check / change them. Sounds like a good probable cause. Will check that tonight.

Anyone think I'm on the right / wrong track?
Regards,
Old man Fix It

 

[mjbst111]

Sounds like you are on the right track. I believe checking the brushes is a delicate process but do-able. Most likely the problem... good luck!

good find with the fuse.

 

[fixit52]

UPDATE:
Removed Alternator , and removed Regulator/brush assembly. One brush appeared to be worn out. Took alternator to local auto parts store... tested no good. Installed new regulator/brush assembly. Tested alternator again... no good.
Bought new alternator.

Trickle charged battery (2 amp) for about 4 hours... full charge. Installed new alternator in car. Reconnected battery... cleaned ground in trunck... cleaned posts and connectors (very clean to begin with). Tesed Alternator at connections.... 12 volts constant on B+ wire (big one).... tested D+ wire with ignition on... 2 - 3 volts.

Tried to start car... No crank condition... i.e. would not turn over at all. Closed hood (wondered if there was a hood interlock... can't find any reference to same in circuit diagram but saw a grounding spring on right front corner between hood and frame... what is it for, anybody know?

Anyway it turned over and started immediately !!! Idled great and battery light was off !!!

Turned off engine and it will not crank again !!! I'm back to square one. The alternator was bad (battery light is now off, etc.) but there is still an intermitent electrical problem in the circuit. Fuse #10 for A/T interlock has not blown again.

I could really use some help in diagnostic procedures starting from the starter and working back... ANybody know of same??

Thanks for all replies,
Old man fix it

 

[nadroj]

my dad has a 85 318i that we keep at our lake house. any way a few weeks back he broke the key for it so we couldnt start it again untill yester day b/c we had to get a new key. so we go to start it and the think won't crank at all. so i got my friends to push it down a small hill in our drive way, while they were pushing it i had it in first and popped the clutch. this caused the motor to start up. After we ran it for a while, drove it to the gas station about 5 miles. It would start right up. so i think it has a problem with losing a little power but not too much so that if we dont start it atleast once a week it will still have enough power to start it, what do you think?

 

[bichmgnt]

Hey Old Man,

I can relate. If you plan on working on this car you should get a Bentley manual for it. What year is the car? That makes a difference in what to look for and which manual to get. The 84-90 3-series Bentley manual has the electrical diagrams for the starting and charging circuits and basic troubleshooting for them. Actually, they all should. It is also great for just about any other problem you may have. If it is one of the earlier 325s you should change the timing belt unless you know when it was done last and it was less than 50K miles ago. There might be a sticker on the fuse box or the Air Flow Meter that has the mileage when it was last changed. It might also be in the driver's door jamb.

Good luck with the intermittent electrical problem. I was an electronics tech for many years and those are the worst.

Steve

 

[bichmgnt]

The hammer trick is if the bendix is stuck and won't throw out like it should. A couple taps on the starter when trying to start it sometimes loosens it up. Doesn't always work but worth a shot.

Steve

 

[Custom 3]

uh...guys...this whole thing about 'pop-starting' and 'popping the clutch' won't work on his automatic transmission.