need help with ignition coil circuit 98 2.0 beetle

[dave5688]

I have a 1998 2.0 beetle with a problem with the ignition coil circuit. I have spark on cylinders 1 and 4 only and only power into the coil on one feed. not sure if it is a wireing problem or maybe ecm or ignition switch. I cant find any info on where the coil feeds from. any help would be appreciated.

Thanks

[MyOtherRidesAVette]

This what you're looking for? Sorry I can't do it in a .pdf
It's a .bmp which I'm not real familiar with working with. I don't know if you can save from these and then print or not. And sorry about the "jiggers" in the lines, I have to capture in three sections.
http://newbeetle.org/forums/attachme...1&d=1316402015
http://newbeetle.org/forums/attachme...1&d=1316402172
http://newbeetle.org/forums/attachme...1&d=1316402172
Or if you can print the post. Maybe print the post.

MORAV

[dave5688]

thanks for the reply. I dont think my wire colors match. maybe this is a different year. it does help give perpective. hase anyone ever run into this before?

[MyOtherRidesAVette]

I pulled this from the Bentley Repair Manual for the '98 2.0L AEG. However, they NEVER change wire colors from year to year. As a matter of fact this should be the same diagram for all AEG engines.
It's possible the wrong diagram is on the Bentley. But the routing should be the same. Do you know how to read the diagram, they are a little different than many are used to seeing.

M.

[dave5688]

Well it looks like one ground from eng compartment. 2 lines off the ecm 80 pin connector and one off a 10 pin connector left side of engine compartment. Not sure but the ones off the ecm...are those grounds and is the one off the 10 pin is that hot. not sure what i am reading there.

[MyOtherRidesAVette]

I'm would assume the two downstream of the ECM, #71, #78 are communication leads, as they are very low voltage at .5 mm² (<20ga). I know, the Bentley wiring schematics are a bitch to read.

[geniushanbiao]

I checked the wiring diagram here. There are 4 wires going into the coil. The Black/Violet is 12V power and it's hot in RUN or START. The brown wire is ground. The other two which are Green/Brown and Green/Yellow are from the ECM so I think they are used for pulses.

And, I have to say if 2&3 are not firing then there is 99% that the coil itself is bad....I had a very similar problem but mine was that 1&4 were not firing. I changed the coil and the problem was all gone.

[dave5688]

I was thinking coil but i replaced it because it was cracked about 6 months ago. It was one I got off of ebay really cheap. maybe it didnt hold up. Anyone know a good test for a coil. ohm meter or whatever. You have all been a big help.

[MyOtherRidesAVette]

Here you go, bench testing -
Coil Test - Testing Your Ignition Coil - Coil Resistance Test - How To Test Your Ignition Coil With an Ohmeter

M.

[dave5688]

thanks for the link. Ill try it out. I wonder what the specs are. I guess anything out of the ordinary is bad

[geniushanbiao]

The specified test for the AEG coil can be found in Haynes manual which you can take a look in any Autozone or Pepboys...What I remember is that to measure the resistance of the secondary coils which is between #1 and #4, and then #2 and #3 since 1&4 use the same secondary coil and 2&3 use another one. I can't remember the actual value but they can't be too much different.

[dave5688]

Ok i will check it out. I was loking for a cracked coil today for a tester, but couldnt find one anywhere.

[dave5688]

did an ohm test on the coil and didnt find anything that tells me bad coil. local import repair shop said it sounds like a coil but seeing as i replaced it 6 months ago i am unsure. it was a cheapy off of ebay so who knows. I cant find a cracked one for test purpose anywhere. i hate to spend the money on a new one if it is not bad. I dont know what to do. I have traced leads on every circuit but it is weird. I cant find continuity on the ecm wires. according to my findings, it shouldnt run. there are no markings on the ecm or harness to tell me which lead is which but from coil connector to any ecm terminal i have nothing, unless i am doing something wrong...

[geniushanbiao]

There is a thorough test of the ignition system in the Haynes manual which you can follow. This includes the following things:

1. test the secondary coil resistance. between 2&3, and between 1&4. They should be between 4000 and 6000 Ohms.
2. Pull off the electrical connector, switch ignition to ON then measure pin 2 and 4 with VOLTMETER. There should be battery voltage.
3. Check the ground continuity(I think it's pin 4).
4. connect a LED between pin 1 and 4, crank the engine, the LED should flash
5. connect the LED to pin 3 and 4, crank the engine, it should flash(you can do 4 and 5 together by connecting 2 LEDs).
6. test the resistance of the spark plug wires, should be 4000-6000 Ohms.
7. check spark plug condition and gap, then you can do a spark test. If all these tests succeeded and there is no spark, then the coil is definitely bad.

[dave5688]

OK...THANKS i will give it a try.

[dave5688]

ok..I want to thank everyone for all the info you gave me. I fixed the ignition problem. Coil and connection at coil and she is idling smooth. I do have another issue. The trans is only manually shifting. pulls out in whatever gear you have the shifter in and it wont go into overdrive. I had everything you could think of unplugged looking for the ignition problem. I haven't checked all my connections yet but is there maybe a re set or something that needs done. ce light needs cleared. maybe thats the problem. I know trans problems are another section. I am going to look there.

[MyOtherRidesAVette]

Glad you were able to solve the ignition problem.

I now have the entire AEG Motronic Engine Management wiring schematic in a .pdf file here -
P1128 Error Code and Location of MAF Fuse
This attachment -
http://newbeetle.org/forums/attachme...-43-wiring.pdf
along with the .pdf file above it, Understanding Bentley Wiring Diagrams.
http://newbeetle.org/forums/attachme...g-diagrams.pdf

I'll have a look at the tranny wiring diagram and see what is common in the area that might have been unplugged. I'm thinking maybe the VSS.

M.

[dave5688]

issue solved. I had the codes checked...there were 12...and cleared. The car was in limp mode. now it shifts fine. hopefully it will be ok for a while. I have been doing nothing but working on this car lately. When it is running fine, it is a great little car. it actually runs too good for anna. I see some people on here saying their cars have no power but this car is strong. pretty easy on gas too.

[MyOtherRidesAVette]

Thanks, I don't have to go digging! Glad you're all good!

I have no complaints about the power of the 2.0L, even with the AT, although I do like the Tiptronic in mine for sporty driving. And I have had two 1.8Ts so I do have a basis for comparison! (lol)

Save those .pdf's for future reference, easier than maybe trying to find this thread when it becomes old.

M.

[dave5688]

i will save those files. hopefully i wont need them but who knows. Thanks again vette and everyone else who posted info on here. I must say, I wouldnt have been able to fix this little bug without help.