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'02 s10 blowing ECM 20a Fuse


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Bluestreak66
Novice

Dec 8, 2012, 11:13 PM

Post #1 of 11 (3490 views)
'02 s10 blowing ECM 20a Fuse Sign In

I have a '02 s10 2.2 The truck will start run for 30 sec and then blow the 20a ecm fuse. That fuse is for continuous ecm power as well as power to the fuel pump though a relay. The truck ran fine until I had a battery issue, the battery had broken inside and did not have a good enough connection to start the truck or even for the lights to come on. I have since replace the battery and the engine cranks fine. When I was tying to figure out what the problem was, checking battery terminals, engine ground, etc, the relays were clicking on and off from lack of power. Would a fuel pump fail because of this and draw 20+ amps? Truck runs fine for 30+ secs, no miss or hesitation. How would I test this my multimeter only goes up to 10a?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 9, 2012, 7:00 AM

Post #2 of 11 (3435 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

The only way you are going to find out is to start isolating some of these circuits or measure the draw for each one. I would probably start out by unplugging the fuel pump and providing an alternate power source to run it on and see what happens. Just make sure you fuse whatever you power it with, preferably and external battery.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Bluestreak66
Novice

Dec 9, 2012, 7:27 AM

Post #3 of 11 (3430 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

I have a fuel pump sending unit I planned to just swap since my fuel gauge hasn't worked correctly for a while and I have a spare one. But say It ends up being the ecm blowing the fuse, my wiring diagrams show it wired into the ecm but I have no way of knowing what is powered from there what could I check? The ecm is also powered by a 15 amp fuse that does not blow.


(This post was edited by Bluestreak66 on Dec 9, 2012, 7:40 AM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 9, 2012, 7:56 AM

Post #4 of 11 (3418 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

Yes, I'm afraid you're right. We don't know what the PCM does with that power. Make sure that pump you are using is the right one for the flex fuel engine yours has.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Bluestreak66
Novice

Dec 9, 2012, 8:19 AM

Post #5 of 11 (3413 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

Im not sure what the fuel pump assembly is from but has a new pump in it. I know its from a 98+ s10. What is the difference in the pump higher volume? Are they physically the same? I am going to pull the pump here after while I'm just trying to get info together right now.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 9, 2012, 8:22 AM

Post #6 of 11 (3408 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

If you're putting junkyard pumps in there, then I'm not real surprised that you're having problems.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Bluestreak66
Novice

Dec 9, 2012, 9:55 AM

Post #7 of 11 (3399 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

OK well thank for your help I can see where this is going at this point, Its a brand new pump by the way a guy at work gave it to me.


Sidom
Veteran / Moderator
Sidom profile image

Dec 9, 2012, 11:42 AM

Post #8 of 11 (3390 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

One thing you can do that may help you out is get a 12v test light. Hook the clip to batt +, then touch the engine to make sure it lights up. Then take the fuse out of the socket and probe the load side terminal, if the light lights up, that would indicate you have a short in that circuit. You can start disconnecting loads until the light goes out. If you are unsure about which one is the load, hook the test light up to ground and it's the terminal with no power to it....

Like HT said you also want to isolate the circuits because they do feed each other, so you want to make sure you are working with the right circuit.

While not totally scientific, I've noticed that when a short is close to the box, it blows the fuse instantly, when the short is a long ways away from the box it takes just a little bit longer to pop the fuses........30 seconds is a bit too long, so I don't know if this one fits this scenario......


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 9, 2012, 11:48 AM

Post #9 of 11 (3382 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

It would be pretty hard to use the test light trick if the engine has to run for 30 seconds to blow. The normal loads will light the light.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
Veteran / Moderator
Sidom profile image

Dec 9, 2012, 11:54 AM

Post #10 of 11 (3378 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

Yea the 30 seconds thing is kinda weird but if it lights up the light with the key off then there is a short in that circuit. The normal loads will show continuity but won't light a 12v powered test light....


Bluestreak66
Novice

Dec 9, 2012, 12:43 PM

Post #11 of 11 (3368 views)
Re: '02 s10 blowing ECM 20a Fuse Sign In

I found the problem. I put a 20a resettable fuse inline with some alligator clips, jumped from the Battery Positive on the fuse block to the load side of the relay with the relay out so the fuel pump would run continuosly. I put a new fuse in the ecm slot and started the truck, the resettable fuse trips out every 30 sec or so and kills the truck. ecm fuse does not blow. even with the key off I can jump the relay and the the reset fuse trips. Its drawing a ton of power because the jump wire rated for 30a get hot. I have never seen a pump fail like this so It had me stumped for a while. As for the answers about compatibility on the fuel pumps, flex fuel pump has different wiring and also the fuel line sizes are different as I found out on another forum. I have since pulled the pump and confirmed this. I am almost positive it is the fuel pump as there is no curent draw with the pump unplugged so no short anywhere besides the pump. I thought filter may be plugged but truck runs fine with no other symptoms.






 
 
 






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