1989 bmw 325i no Injector pulse

10

Asked by Oct 04, 2013 at 10:00 PM about the 1989 BMW 3 Series 325i Sedan RWD

Question type: Maintenance & Repair

Car will run good all day on ether but will not start without .Obcc gives fault code 1252 - Fuel Injector #2 (single or group). Crank sensor was replaced, main relay seems ok, feul presure good, just no pulse going to the injectors. Any ideas ? I'm at a lose, mechanic couldn't figure it out either..

7 Answers

113,875

Recheck all of the ECM powers and grounds, remember that the injectors are triggered by a negative pulse, so one side is battery voltage and the other side is the trigger signal negative pulse, so usually if you loose the injector pulse then it is most likely the computer but make sure you have all of the necessary power and ground pathways, a service manual with wiring diagrams will really help with this.

10

all the grounds have been checked, they are good. Mechanic said he checked the computer it seems to be ok, only thing I can think is maybe the chip blew, I don't think he pulled the computer.

113,875

He needs to check for the injector pulse at the ECM, if it is there and not at the injectors then a wiring problem needs to be sorted out, if it is not at the ECM then the problem is in the ECM.

1 people found this helpful.
10

can you tell me the procedure for checking injector pulse at the ECM?

1 people found this helpful.
113,875

You need to find the injector driver wires coming out of the ECM, a wiring diagram should help with the color and location, once you locate the wires then using a low draw test light, led is preferable or a "noid light" this will prevent and injector driver damage due to high current draw, tap into the driver wire with one end of the light and put the other on a positive power source, crank the engine, the light should flash rapidly, if it doesn't then the usually the ECM needs replaced or rebuilt. If it does then you need to trace out the wiring until you find the broken circuits. Of course all of this is assuming that all of the power and ground pathways and sensors have been check and found to be good.

10

thanks for the info I'll besure to check

10

I found another ECM, confirmed good, and installed it .. still nothing. Any other ideas?

Your Answer

3 Series

Looking for a Used 3 Series in your area?

CarGurus has 32,463 nationwide 3 Series listings starting at $900.

ZIP:

BMW 3 Series Experts

  • #1
    Tom Demyan
    Reputation
    5,610
  • #2
    Robert Charlson
    Reputation
    1,770
  • #3
    Matt Mankinen
    Reputation
    1,380
View All

Related Models For Sale

Used BMW 5 Series
398 Great Deals out of 16,341 listings starting at $1,650
Used BMW M3
15 Great Deals out of 1,645 listings starting at $6,599
Used Ford Mustang
253 Great Deals out of 36,696 listings starting at $2,500
Used BMW 6 Series
57 Great Deals out of 2,542 listings starting at $5,085
Used BMW 7 Series
120 Great Deals out of 4,795 listings starting at $3,950
Used Honda Accord
447 Great Deals out of 102,248 listings starting at $800
Used Chevrolet Camaro
238 Great Deals out of 28,790 listings starting at $1,800

Used Cars For Sale

2018 BMW 3 Series For Sale
84 Great Deals out of 8,599 listings starting at $27,976
2017 BMW 3 Series For Sale
62 Great Deals out of 2,111 listings starting at $22,896
2016 BMW 3 Series For Sale
8 Great Deals out of 936 listings starting at $15,350
2015 BMW 3 Series For Sale
198 Great Deals out of 4,992 listings starting at $12,498
2014 BMW 3 Series For Sale
137 Great Deals out of 2,456 listings starting at $9,995

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.