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Eric
Eric, Automotive Repair Shop Manager
Category: BMW
Satisfied Customers: 29949
Experience:  20+ yrs. experience as repair shop manager and technician.
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My name ***** ***** and I'm having an issue with my 1985 bmw

Customer Question

hi my name ***** ***** and I'm having an issue with my 1985 bmw 318i it cranks but there is no power coming out of the coil and I have replaced it twice
JA: Thanks. Can you give me any more details about your issue?
Customer: I'm getting power to the coil but no spark is coming out of it
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Submitted: 9 months ago.
Category: BMW
Expert:  Eric replied 9 months ago.

HI,

I am sorry that you have not been helped yet. I just came online and saw your question

Ok, you need to test the ignition control unit

1. Check power supply for TCI control unit.
a. Check voltage between terminals 2 (+) and 4 (-) on disconnected control unit plug. With ignition on, battery voltage should be present.
b. Check voltage drop between terminal 2 on control unit plug, and battery negative.
c. Check voltage drop between terminal 4 on control unit plug, and battery positive.

2. Check closed circuit current for TCI control unit.
a. Connect ammeter in series on ignition coil (terminal 15).
b. Turn on ignition.
c. Ammeter should show zero amperes after approximately 1 second.

3. Check control unit ground.
a. Disconnect plug at control unit.
b. With ignition on, check for continuity between terminal 31 of control unit (not the plug), and ground. Resistance should be about 0 Ohms.
c. If resistance is excessive, repair wiring as necessary.

4. Check control unit output.
a. Connect an ammeter in series on ignition coil terminal 15. With engine running at 1000 ± 50 rpm, 1.7 - 7.0 amperes should be indicated.
b. If amperage is low, eliminate contact resistance.
c. If amperage is high, replace ignition control unit.

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