3VZE EFI shorting, take a look.
09-12-2014, 10:06 AM
#1
Registered User
Thread Starter
3VZE EFI shorting, take a look.
Hey guys, just wanted to say I already looked threw the forums but nobody has this similar issue. So the problem is i'm blowing EFI fuses so I got a short. My entire truck is in pieces to check all the wiring.
Things i've checked
-o2 sensor, wiring is fine sensor is fine
-fuel pump wiring there doesn't appear to be any cuts and i didn't find it grounding out anywhere
-checked in the engine bay nothing is grounding to the exhaust
-checked the harness and that also appeared fine, checked each wire one by one to see if its grounding out anywhere and nothing.
-changed cor relay and no difference
Just to give back story the fuse blows when I try cranking the engine, sometimes it'll actually turn on and idle for maybe 2-3 minutes and POP goes the fuse.
I also took out my fenders and i do got a few holes leaking water inside so that defiantly is causing a short but i've cleaned all the water from wires and it hasn't rained in days. Is there something i'm missing? Anything else I could check? Maybe the ECU is done? I really don't where else to go from here. Thanks guys.
Things i've checked
-o2 sensor, wiring is fine sensor is fine
-fuel pump wiring there doesn't appear to be any cuts and i didn't find it grounding out anywhere
-checked in the engine bay nothing is grounding to the exhaust
-checked the harness and that also appeared fine, checked each wire one by one to see if its grounding out anywhere and nothing.
-changed cor relay and no difference
Just to give back story the fuse blows when I try cranking the engine, sometimes it'll actually turn on and idle for maybe 2-3 minutes and POP goes the fuse.
I also took out my fenders and i do got a few holes leaking water inside so that defiantly is causing a short but i've cleaned all the water from wires and it hasn't rained in days. Is there something i'm missing? Anything else I could check? Maybe the ECU is done? I really don't where else to go from here. Thanks guys.
09-12-2014, 12:30 PM
#2
Registered User
Join Date: Sep 2007
Location: San Francisco East Bay
Posts: 8,250
Likes: 0
Received 820 Likes
on
648 Posts
The ECU is powered continuously (BATT: A1) through the EFI fuse, and also with switched power through the EFI relay (+B and +B1: A12, A13). So for the ECU to be the problem it would have to be "partly" shorted. Possible, but not likely.
1. Does the fuse blow as soon as you turn to key-on? If so, it's not the fuel pump, as the COR hasn't closed yet.
2. The EFI also powers the VSVs on the fender. (My schematics show a white-red wire.)
3. When you say the wiring is "fine," does that mean you looked at it, or something else? I'm not sure what I would look at to see an electrical short.
I would use a multimeter. I'd start by measuring resistance to ground through the B+ terminal on the diagnostic connector with KEY-OFF (this disconnects B+ from power). This isn't going to be easy; the O2 sensors alone are only about 5 ohms, but start by disconnecting them. Then the VSVs. Then the COR. If you get a sudden jump in resistance, I would concentrate on that component. It will really help if you have an assistant to watch the meter while you are carefully wiggling the respective wires.
Your most likely source of a short is the O2 heater wires (it's a hellish environment), but if you've got rain on the wiring, well, all bets are off.
1. Does the fuse blow as soon as you turn to key-on? If so, it's not the fuel pump, as the COR hasn't closed yet.
2. The EFI also powers the VSVs on the fender. (My schematics show a white-red wire.)
3. When you say the wiring is "fine," does that mean you looked at it, or something else? I'm not sure what I would look at to see an electrical short.
I would use a multimeter. I'd start by measuring resistance to ground through the B+ terminal on the diagnostic connector with KEY-OFF (this disconnects B+ from power). This isn't going to be easy; the O2 sensors alone are only about 5 ohms, but start by disconnecting them. Then the VSVs. Then the COR. If you get a sudden jump in resistance, I would concentrate on that component. It will really help if you have an assistant to watch the meter while you are carefully wiggling the respective wires.
Your most likely source of a short is the O2 heater wires (it's a hellish environment), but if you've got rain on the wiring, well, all bets are off.
09-12-2014, 12:49 PM
#3
Registered User
Thread Starter
The ECU is powered continuously (BATT: A1) through the EFI fuse, and also with switched power through the EFI relay (+B and +B1: A12, A13). So for the ECU to be the problem it would have to be "partly" shorted. Possible, but not likely.
1. Does the fuse blow as soon as you turn to key-on? If so, it's not the fuel pump, as the COR hasn't closed yet.
2. The EFI also powers the VSVs on the fender. (My schematics show a white-red wire.)
3. When you say the wiring is "fine," does that mean you looked at it, or something else? I'm not sure what I would look at to see an electrical short.
I would use a multimeter. I'd start by measuring resistance to ground through the B+ terminal on the diagnostic connector with KEY-OFF (this disconnects B+ from power). This isn't going to be easy; the O2 sensors alone are only about 5 ohms, but start by disconnecting them. Then the VSVs. Then the COR. If you get a sudden jump in resistance, I would concentrate on that component. It will really help if you have an assistant to watch the meter while you are carefully wiggling the respective wires.
Your most likely source of a short is the O2 heater wires (it's a hellish environment), but if you've got rain on the wiring, well, all bets are off.
1. Does the fuse blow as soon as you turn to key-on? If so, it's not the fuel pump, as the COR hasn't closed yet.
2. The EFI also powers the VSVs on the fender. (My schematics show a white-red wire.)
3. When you say the wiring is "fine," does that mean you looked at it, or something else? I'm not sure what I would look at to see an electrical short.
I would use a multimeter. I'd start by measuring resistance to ground through the B+ terminal on the diagnostic connector with KEY-OFF (this disconnects B+ from power). This isn't going to be easy; the O2 sensors alone are only about 5 ohms, but start by disconnecting them. Then the VSVs. Then the COR. If you get a sudden jump in resistance, I would concentrate on that component. It will really help if you have an assistant to watch the meter while you are carefully wiggling the respective wires.
Your most likely source of a short is the O2 heater wires (it's a hellish environment), but if you've got rain on the wiring, well, all bets are off.
1- It blows when I try cranking it, so the CEL turns off as soon as it cranks. Sometimes it'll actually run for a good 2 minutes then just completely die out aka fuse blows.
2-Which fender are we talking?
3-I pulled the entire wire harness in the interior from both sides. Checked each wire one by one for any cuts or melts. Literally spent an entire day doing this.
I've checked the o2 harness already, it was previously covered with electrical tape, took it all off to find everything fine, what a mission that was.
I'll start checking some voltages, i might need to buy a new multimeter my contacts are broken. Working on a budget lol.
09-12-2014, 01:06 PM
#4
Is your Check engine light on??
I hate to see people pull the whole truck apart for something that can be located with a few tests of the circuits involved.
Just when did this start??
Do any work on the truck just before it started??
Is the fuse loose in the socket causing it to arc and draw to much current?? Thus making it open.
You are using the correct fuse for the max current draw for that circuit.
fuel pump starting to go bad drawing to much current comes off the top of my head.
Could be a clogged sock on the pump or the filter if it is not the pump.
I hate to see people pull the whole truck apart for something that can be located with a few tests of the circuits involved.
Just when did this start??
Do any work on the truck just before it started??
Is the fuse loose in the socket causing it to arc and draw to much current?? Thus making it open.
You are using the correct fuse for the max current draw for that circuit.
fuel pump starting to go bad drawing to much current comes off the top of my head.
Could be a clogged sock on the pump or the filter if it is not the pump.
09-12-2014, 01:37 PM
#5
Registered User
Join Date: Sep 2007
Location: San Francisco East Bay
Posts: 8,250
Likes: 0
Received 820 Likes
on
648 Posts
Doing any sort of electrical work without a multimeter is a complete waste of time. You can't SEE a short.
But since your fuse does not blow until you turn to key to STArt, we're really narrowing things down. It's not the O2 sensors, the VSVs or the ECU, as those are all powered with Key-On. The only thing added with STArt is the COR closes and powers the Fuel Pump.
The FP terminal in the diagnostic connector connects straight to the fuel pump (bypassing the COR), so you could measure resistance to ground from there (with KEY OFF). But that won't help much, as the resistance of the fuel pump is probably only 2-3 ohms. Instead, I'd unhook the fuel pump at the tank. If the fuse still blows in STArt, then your short is in the line from the COR. If the fuse doesn't blow, I'd suspect the fuel pump for the reasons given by Wyoming9.
[The VSVs aren't on the fender, but rather the fender apron (the lining of the engine compartment) on the passenger side just aft of the junction/fuse box.]
09-12-2014, 01:58 PM
#6
Registered User
Thread Starter
I paid $70 for MY first digital multimeter; but that was a long time ago. You won't be able to buy one like mine for that kind of money. http://www.harborfreight.com/7-funct...ter-98025.html
Doing any sort of electrical work without a multimeter is a complete waste of time. You can't SEE a short.
But since your fuse does not blow until you turn to key to STArt, we're really narrowing things down. It's not the O2 sensors, the VSVs or the ECU, as those are all powered with Key-On. The only thing added with STArt is the COR closes and powers the Fuel Pump.
The FP terminal in the diagnostic connector connects straight to the fuel pump (bypassing the COR), so you could measure resistance to ground from there (with KEY OFF). But that won't help much, as the resistance of the fuel pump is probably only 2-3 ohms. Instead, I'd unhook the fuel pump at the tank. If the fuse still blows in STArt, then your short is in the line from the COR. If the fuse doesn't blow, I'd suspect the fuel pump for the reasons given by Wyoming9.
[The VSVs aren't on the fender, but rather the fender apron (the lining of the engine compartment) on the passenger side just aft of the junction/fuse box.]
Doing any sort of electrical work without a multimeter is a complete waste of time. You can't SEE a short.
But since your fuse does not blow until you turn to key to STArt, we're really narrowing things down. It's not the O2 sensors, the VSVs or the ECU, as those are all powered with Key-On. The only thing added with STArt is the COR closes and powers the Fuel Pump.
The FP terminal in the diagnostic connector connects straight to the fuel pump (bypassing the COR), so you could measure resistance to ground from there (with KEY OFF). But that won't help much, as the resistance of the fuel pump is probably only 2-3 ohms. Instead, I'd unhook the fuel pump at the tank. If the fuse still blows in STArt, then your short is in the line from the COR. If the fuse doesn't blow, I'd suspect the fuel pump for the reasons given by Wyoming9.
[The VSVs aren't on the fender, but rather the fender apron (the lining of the engine compartment) on the passenger side just aft of the junction/fuse box.]
Last edited by Markarino; 09-12-2014 at 02:00 PM.
09-21-2014, 07:01 PM
#7
Registered User
Thread Starter
Just to close off the thread I found my issue. The water getting in threw the fenders was getting into contact with the inside fuse panel causing a short. So pretty much on a sunny day it runs fine, while it shorts after a rain storm. I'll have to take it to a body shop to fix the inner fender rust. Just a heads up for anybody else who might run into this issue.
Trending Topics
Thread
Thread Starter
Forum
Replies
Last Post
