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Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: BMW
Satisfied Customers: 1606
Experience:  Owner at Carolina Auto Service & Sales , 20 years Experience in Foreign & Domestic vehicles
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A friend has a 2000 bmw 740i. i worked in a transmission

Customer Question

a friend has a 2000 bmw 740i. i worked in a transmission shop many years. i tooking his trans out and sealed the front. i had the battery disconnected about 12 days. the battery is weak. had to jump it off. trans worked fine but the speedometer did not. soon it started in higher gear. snapon scanner said it was a speed senser. i replaced both. did not help. also tack does not work and the gauges do crazy things. does the ecm need resetting? i have run into a bad ecm ground on other cars. maybe that is the problem. i dont know. can you help me?
JA: How old is the battery? And have you tested it with a voltmeter?
Customer: i do not know how old the battery is. he just bought it. i have not tested it but you have to jump it or put a charger on it if it sits a few days
JA: Are you fixing your 740i yourself? What have you tried so far?
Customer: it is my friends. it might as well be mine. yes i am fixing it. the only thing i have done is seal the trans and put both speed sensors on it.
JA: Anything else you want the mechanic to know before I connect you?
Customer: i cant think of anything
Submitted: 1 month ago.
Category: BMW
Expert:  Chad Farhat replied 1 month ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 1 month ago.

hey man how are you

1- we have to start with testing battery for 12 volts & under load do you have 12 volts

2- with car running at the battery with voltmeter , do you have 14 + volts with headlights, ac , radio on etc..

3- after you replaced the VSS sensors did the fault clear with your scanner, can you pull up the sensors and go down the road and see if they are reading

or is it not moving or going in gear ?

4- as far as bad ground and bad ecm , yes that is possible, but we have to start with a good 12volts & alternator charging for theses cars all of modules involved and if not enough power generated they will shut down or you want be able to clear the faults .

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 1 month ago.

Please let me know if you need anything else on it, just reply back and we will continue

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Thank You
Chad Farhat
ASE Certified Technician

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