Blowing Injector Fuse

criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

Help!
First I've read Sam's Noob Guide.
Second, I have the second generation fuel filter head, the one with no supposed problems.

Here's the issue.
It has happened a couple times and I'm not sure what caused it. The injector fuse (box under the hood with the 25amp fuse) blows, replace and runs again. Happened once, the again 3-4 moths later. Now I'm out I. The middle of nowhere and every time I turn the key the fuse blows.
I'm heading outside to unplug all the injectors and see if it blows again, then plug them in one at a time.
Anyone had this problem?
Theory's?

Anyone want to buy a CRD with 1700000kms? Replace timing belt, up todate service, ltd...ect?

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criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

Ok. So I found that #3 or #4 injector when plugged back in cause the fuse to blow......now what?

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flash7210 · **Posted:** Fri Jan 30, 2015 2:29 pm

Sounds like those injectors are bad.
I would pull all four of them and send them to a shop that can test them.

Is that 1 million 700 thousand kilometers ??

criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

Ya no it's 170 thousand

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papaindigo · **Posted:** Fri Jan 30, 2015 3:01 pm

Does the fuse blow:
1. when you plug those injectors back in with the ignition off
2. as above but with ignition on (as in power to dash but not to crank the engine)
3. neither of the above but when you try to crank the engine.

If 1 or 2 you have a short to ground somewhere in the injector wiring circuit

If 3 probably the same. I suppose it's possible for a bad injector to blow a fuse but how it would blow a 25 amp fuse I have no clue.

If you have a 06 I'd start by looking at where the wiring bundle goes behind the fuel filter head bracket.

I am by no means an auto electric person so take what I say with some salt grains but you do need to be more specific about exactly the conditions are that cause them to blow especially as related to the ignition.

criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

Thanks for your help.
So it blows with the ignition on, and all injectors plugged in.

I unplugged all injectors turned the ignition on and plugged the injectors in one at a time. Got to #3 and it blew the fuse. Checked the harness down towards where it disappears (doesn't go behind the filter but rather below and in behind the battery)
Spoke to a fuel injection place. . Said it sounds like the injector, but could be the power module (very doubtful though). I'm just looking for a multi meter to test the resistance to see if this one injector is different than he other 3. Then call him back to see if he has one in stock.

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criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

Ok. So after some discussion with the fuel injection guy, and testing the resistance on the suspect injector the rest and his new one. We decided that it is not the injector. Put the old one back in, and it started! I havnt a clue? Anyone's guess?

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papaindigo · **Posted:** Fri Jan 30, 2015 6:19 pm

Someone who is better at electrics than me will have to weigh in but as I understand it:
1. all injectors unplugged.
2. ignition switch on (e.g. the "on/run" position not the "start" position per the owner's manual). NOTE I would be curious what would happen if you repeated this test with the ignition switch in the "ACC" position)
3. injectors plugged back in one at a time at which point when #3 was plugged in the fuse blew.

I would have thought that regardless of the ignition being in the "on/run" position but also with the vehicle not ever started that the ECU would not have been "engaged" in such a manner as to provide any signal/current to the injectors certainly not enough to blow a 25amp fuse.

I still suspect a short somewhere but cannot offer any advise on how to test for same.

Mike92104 · **Posted:** Fri Jan 30, 2015 6:47 pm

Most likely an intermittent short in the injector harness.

criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

Anyone have any idea how to find an intermittent short?

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Billwill · **Posted:** Sat Jan 31, 2015 5:00 am

Which fuse number is actually blowing....there are several 25 Amp fuses under the hood.
Are you getting any codes stored?

You may need to physically trace the leads to the injectors ie. unwrap all the insulation tape from them to trace their exact route...making sure they are not snagging on anything. This way you will also be sure that the wires do not go behind the fuel filter head. Then once you have fixed the problem you tape up all the wires nice and neatly again....been there and done that a few times!

What year is your CRD? You can download the relevant year Service Manual here:http://www.colorado4wheel.com/manuals/Jeep/KJ

For the 2006 CRD you need to go to the "wiring" section, Page 8W-30-19, for the 2005 CRD you need page 8W-30-35.
The 2005/6 CRD circuit diagram does not specifically show an "injector " fuse...all four injectors get power on both sides of the injectors directly from the ECM...I need to know the fuse number please.

To test the injectors you need to have a digital multimeter....a simple one will do.

Then disconnect the battery, pull off the connectors on the ECM which is on the side fender on the driver's side.
Pull of each connector to the injectors.

With the multi meter set to OHMs, first put the two meter leads across the injectors directly ie. across pins 1 and 2 as the diagram shows with the plugs disconnected. Make sure you are not touching the meter leads with your hands at the time or you will be measuring the resistance through your body. Make a note of the reading and repeat for each injector...they should all be about the same reading of a about a hundred Ohms at I believe.

Now with the injector leads all still disconnected and the connector C1 pulled off the ECM, measure the Ohm reading of the leads to each other ie. test the Orange/Brown wire and the Brown/Yellow wire of injector #1 to each other.....there should be an infinite reading seeing as the two wires are going nowhere.....repeat with the other injector leads.

Then still with the leads disconnected, test the Ohm reading of each of the above wires to a good clean engine point...there should likewise be no reading as the leads are in theory floating and going nowhere...repeat for all leads and you can try wriggling the leads about while you are taking these readings.

Then measure across the ECU pin pairs ie. connector C1 pin 25 and 74 for injector #1 etc. and do so with all the other ECU outputs to the injectors. Note that these readings will be dependent on which way around the black and red wires of the meter are when placed on these ECU pins so make a note of each position's Ohm reading with first the red and black wire the one way around and then reversed....any major difference here between the four different ECU outputs would point to a bad ECU unfortunately but that would tend to give a solid error...not intermitant!

gmctd · **Posted:** Sat Jan 31, 2015 4:12 pm

If it happens again and you have not located short-circuited wiring to #3 or #4 INJ, as above^^^:
Set DV\CM to AMPS function
Set to highest current range, ~50a^
Pull blown 25a fuse (#26 from ASD relay)
Insert RED\POS\+ lead into cavity 36
Insert BLACK\COMM\- lead into cavity 37
Observe DV\CM while someone switches IGN to ON position - not START

If ECM test-pulses Injectors, should see instant current drain of less than 25A, then dropping to some quiescent value after ECM normalizes

Immediate large current drain could indicate failing INJ driver module inside the ECM - immediately turn IGN switch OFF

However, it is more likely that a short-circuit condition exists in the wiring between the INJ connector and the ECM connector, either between the wires, or from wires to ground

criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

So...happened again.

My mistake, yes the wiring harness goes behind the filter. I grabbed the harness and moved it, replaced the fuse and it worked. Just waiting for the ferry to home then I'll have to pull things apart and have a look.

The fuse is number F26

Thanks for everyone's help, I hope this may also help someone else out one day

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criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

Ok found it (I hope anyway).

Yes it was behind the filter. It rubbed through the tape, sock and wires just to the point it touched.

Here is after I fixed it. I used vinyl hose and rubber hose to protect from future issues.

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papaindigo · **Posted:** Mon Feb 02, 2015 10:07 am

Was I you I'd replace that 1st gen fuel filter; won't do anything for your wire issue but will help prevent air in fuel issues

criver · **Joined:** Sun May 20, 2012 5:56 pm **Posts:** 15

Thought that was a second generation filter head?
Doesn't the first generation have a blue plug?

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papaindigo · **Posted:** Mon Feb 02, 2015 12:44 pm

Nope - 1st gen heater plug (on right viewed from from) is smaller than the temp probe plug (left) and both are the same color - 2n gen the plugs are close to the same size and the heater plug has a blue cap holding the new wire in the new plug head.

You can get the head and wiring from here http://idparts.com/catalog/product_info ... ts_id=4723 although they appear to be out of stock (on order) right now. New head comes with new filter and WIF sensor. New wires don't match the color of original wires just splice based on best size match. Be sure to disconnect battery to avoid shorts while doing wiring.

Blowing Injector Fuse

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