Ignition fuse blows during cranking

Is there any kind of remote start or alarm system spliced into the ignition circuits that you can see?

No but I am suspecting the ignition switch to be shorted beacuse the S wire has voltage with just the kery on engine off and there should not be voltage unless it is in start position ( cranking position). do you agree? is it possible the ignition switch to be the source of short?

Any other tips why I see the short in fuse 40 is seen when I place a test bulb instead of fuse 40. What else should i Look at?

Fred975 wrote:

Any other tips why I see the short in fuse 40 is seen when I place a test bulb instead of fuse 40. What else should i Look at?

Possibly because there is a path to ground through the control side of the oxygen sensor heater relay.
You can remove that relay and see if the bulb doesn't quit.
If there was a true short to ground in that circuit, the fuse would open with the just the key on. It wouldn't matter if the engine was cranking.

Thank you Noah for good tips.I do really appreciate you took the time and pulled the diaggram on line. As you see in the diagram that Fuse 40 feeds a lot of components.
PCM
O2 sensor relay
Ignition coil
Alternator
Fuel pump relay
I agree O2 sensor has solid ground but I did remove the O2 relay and I even cut the Blaclk and white wire ( power wire from F40) to isolate the short. Also I have cut the black /White wire feeds the ignition coils to isolate the short so Right now I have only power going to fuel pump relay and Pcm left connected, but still the bulb illuminates. I tested the wire to PCM and it is not grounded but still the bulb stays lit. Talking to you helps me think out of the box.Please keep suggesting other tips and hopefully with your guidance I isolate the short. Thanks agian.

Interesting...
And with this wire cut, does the fuse also open while cranking the engine?
I'm having trouble finding a detailed power distribution diagram. The color one from Mitchell just has an arrow that says "engine controls, starting/charging".

Hi Noah,

The short is still evident anb the light bulb is still lit. The answer is yes. How did you paste the diagram?I have the power distribution diagram I use Alldata they hve all diagrams for 2004 Suzuki grand vitara 2 wheel drive ( rear wheel drive). May goal to is shut off the that bulb light becaues it show the short still active. Do you agree?

Just to be perfectly clear, the answer is "yes, the fuse continues to blow"?
The goal should be to get the car running, I honestly don't care much about what the bulb thinks if the fuse doesn't blow...

You will have to save the diagram as a .png .bmp format, then click the tab that says attachment, find the file you want to upload, then click insert.

Hi Noah,

I have already lost one PCM and I am on my econd computer because of this short issue and fuse blowing. That is why my priority is to take care of the short and get the light bulb to turn off first otherwise I will burn the second PCM. As you may know for Suzuki since nolonger is made in USA it is hard to find parts. But I do appreciate you are providing tips to guide me through to find a resolution for the short. do you have the ignition circuit what else could be causing the short? thank you so much. Do you need tme o send you the power distribution.

I understand your apprehension. I am not convinced by the results of the bulb test in this case however. Correct me if I've misinterpreted your posts. You stated that with the key on, with a bulb in place of the fuse, the bulb lights. But with the key on, and the fuse in place, the fuse doesn't blow. Only in the cranking position does the fuse blow, so only in the cranking position is the cisuit over loaded. So we can't exactly say the bulb is lit with the key on for the same reason that the fuse is blowing with the key in the cranking position.

I agree that is the dilemma. with Bulb in place and Key on, the bulb is lit but not blowing any fuse. Also as you stated when the fuse in place is not blowing with key on position, only in cranking position. If the circuit is overlaoded is it possible the ignition switch causing the overload and messed up causing the overlaod. I forgot to mention the S wire at the starter shows voltage of 8 volt with key on only. The S wire is not supposed o have voltage with only key on, it issuppose to have voltage only in cranking position.

I had a truck blowing a PCM fuse yesterday because of a short to ground and it made me think of the problem you're having.
I found it with an ohm meter in the fuse box on the leg of the fuse that feeds the PCM

You can see here it's a dead short to ground.
Not sure what a good circuit would look like, I did the same test on the TCM fuse that did not have a problem.


I then reset the min max values and began wiggling the harness.

You can see the max value changed when I was close to the short.

This test may or may not be helpful. While I agree the bulb should not be lit during your testing, I'm still very confused as to why the fuse only blows while cranking...

Thank you Noah for thinking of my issue. Can I ask you this test indicates the wire that is feeding the PCMis shorted or touching the metal part some where? So let us suppose that would be the case in my Suzuki too once I do this test. if I by pass that the wire that feeds the PCM then ,the short should go away and the bulb should turn off do yuou agree? Regards. Fred

While I do agree in theory, I'm trying to get you away from the bulb test to try and quantify the short condition with the key on engine off that for some reason doesn't blow the fuse.

i would trace the whole length of the s wire , you may have solved your problem ,seems to me you got another wire somewhere that is almost fully bleeding into the s wire ,so the whole circuit has to be checked ,from switch, fuse and leading up to the starter .

also make sure one or two strands of wires from nearby post / connection isnt touching the s wire ! sometimes a quick short will burn all wires onto something except one to just a few strands ! i have seen problems where too much DIE -ELECTRIC SILICONE GREASE bleeds over to another nearby slot , connection , wire etc. thats another reason why you always use this stuff minimally and sparingly ! lol
think about running a thick bead on a board 2 feet .introduce current to the bead , now run many bead off of main bead to different circuits , it will send current to those circuits electrical properties of the silicone !!!

I fully agree and that is the next path that I will be taking after completing the test recommended by Noah. Thank you Rickrick.

ON MY 2011 BUICK LACROSS 3.6 ALSO ,,,,,i got this same problem on my #10 fuse keeps burning when i try to crank it by push button . MY # 10 fuse feeds 3 separate wires that go to IGN to my ecm ...... my PP3 SHOWS THE SAME THING ,I PUT IN A BLOWN FUSE AND IM GETTING my 12 plus volts at power side but green led and sound with o.1 or 0.2 showing on load side ,.the # 10 fuse , shares connections with 3 or 4 other fuses .car ran fine ,went to dr. 3 hrs later got in and would crank , strange ! what did you do brother about this brother ?

I would leave it to Noah to make some recommendations since he is the expert I am just a novice in the electrocal trouble shooting. My humble recommendation is to trace the load side of fuse no. 10 to find out where it s shorted.

Rickyrick wrote:

...i have seen problems where too much DIE -ELECTRIC SILICONE GREASE bleeds over to another nearby slot , connection , wire etc. thats another reason why you always use this stuff minimally and sparingly ! lol
think about running a thick bead on a board 2 feet .introduce current to the bead , now run many bead off of main bead to different circuits , it will send current to those circuits electrical properties of the silicone !!!

While silicon used on computer boards is a semiconductor, I'm quite sure dielectric silicone grease is an insulator. It is used on electrical connections for it's water repellent abilities.
Try a dab on the brushes of a DC brush type electric motor, like a blower motor.