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Matt, Engineer
Category: BMW
Satisfied Customers: 20396
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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95 bmw 325i: convertable..charged batt went to start turned..reader

Resolved Question:

95 bmw 325i convertable battery srarted goiong dead,then i charged batt went to start turned over and now nothin no click nothin its not gettin anyvoltage from key reader what do i do and what and where can i find the part
Submitted: 4 years ago.
Category: BMW
Expert:  Matt replied 4 years ago.

I'd first check the easy things like is the boot light or any other interior light staying on then check that the main battery connections are tight and in good condition also check the earth strap to the engine / gearbox.

Next I'd check the current drain aspect, the best way to find what circuit is causing the excessive currant drain is to fit a current sensing multimeter in series with the positive battery lead on the car and the battery, or use a current clamp meter on the battery positive cable.

A typical current drain with everything off and un-alarmed should be around 0.05Amp and if its higher than this remove a fuse and re-measure, if measurement doesn't change then replace the fuse and remove the next.

Once you've isolated the circuit with the excessive drain check the wiring connections and plugs to components and the wiring harness that runs by the engine bay fuse box - the wiring harness chaffs / rubs through and gets damaged - but its not always easy to see so be careful when checking..

Also check that the alternator is actually charging the battery in the car by taking a battery voltage reading with the engine off then another with the engine running. The 2nd reading should be higher than the 1st and climbing steadily. And also check that the alternator is secure to the engine as this provides the ground for the charging circuit and make sure that the engine / gearbox earth strap is secure and the contacts are clean and bright.

if the alternator appears not to be working - take it to a electrical specialist and ask them to test it as sometimes you can replace just the diode pack and this will repair the alternator without requiring replacement
Customer: replied 4 years ago.
Well the drain isnt my main concern i just let u know all the details of my issue my main issue is the car wont start i had a mechanic look at it And he said it was the key reader
Expert:  Matt replied 4 years ago.

if the key fob isn't disarming the car so the immobiliser won't allow a start then I'd suggest 1st replacing the batteries in the fob and then try re-synchronising the fob as follows:

Method 1:

1. Working from within the vehicle and with the doors shut

2. Turn ignition to position 1 and back to off within 5 seconds.

3. Remove the key from ignition and press and hold the unlock button for 15 seconds during this time press the key lock button 3 times within 5 seconds.

4. Release both buttons.

5. Doors will lock and unlock to show correct programming has occurred.


Method 2:

To do this procedure you need to have one working key and one key that needs to be programmed.

1) Get in and close all doors.

2) Turn on the ignition and turn off quickly. (No more than 5 seconds) to start the process. Next action must take place within 30 seconds.

3) Remove the 1st key.

4) Hold the key up near your left shoulder (this is so it is closer to the remote receiver antenna.

5) Hold down the unlock button and press the lock button 3 times. Release the unlock button and the doors lock which confirms the operation.

6) Quickly repeat steps 4 & 5 for key #2 etc.

If it does not work, try doing the keys in opposite order. Key 2 then key 1, vs 1 then 2.


Method 3:

Alternate if you do not have a working remote

1. Turn key to position 1 five times very quickly 2. Remove key 3. Hold unlock button then press lock button 3 times, release unlock button.

4. If you have another key do the same button pressing within 30 seconds 5. Turn on ignition to finalise.

PLEASE NOTE: This programming procedure programs the remote control part of the key. Any transponder chip for the immobiliser (starting of car) will not be programmed and must be done by a specialist.

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