Jeep Repair Problems? Ask a Mechanic for Answers ASAP
Hello and welcome to JustAnswer, My name is XXXXX XXXXX I will be assisting you.. Do you know what fuse number it is?
Maybe fuse 20?
I don't have it in front of me - its stuck on one of the back fields of my farm
Ok, I looked up the wiring and I believe its fuse # XXXXX which is a 30amp and controls Coil, Ignition, Etc...
lets roll with that assumption
There is a wiring of that fuse.. How ling does it take to blow the fuse?
took awhile at first - could replace and go...
Last night - as soon as u cranked the engine it blew - car was very hot
And now does it blow as sonn as you install it?
went thru 4 fuses
Ok, great! The issue will be easy to find then.. If you can read the Wiring Diagram.. That fuse supplies to Coil, Alternator, PCM, O2 Sensors.. I would like for you to start unplugging these one at a time until the fuse stops blowing.. And based on the my history, Id start with the O2 sensors
If you get back out there and the fuse isnt #20, post back and I will be able to get you the correct wiring diagram
gotcha - read that - if that works..replace that component?
Correct!!! The component you unplugged and it stopped blowing, replace that component...
If you need anything else, feel free to ask... Im here to assist you in repairing your vehicle
Well I want to Thank You for choosing JustAnswer. It was my pleasure assisting you, and if you have any future questions feel free to Request mehttp://www.justanswer.com/car/expert-dodgetech77/ Thank you and have a greatday!!!!! Brad
Well I want to Thank You for choosing JustAnswer. It was my pleasure assisting you, and if you have any future questions feel free to Request me
Here is another wiring:
Plug all of the back in. We are going to check the Crank sensor and the Cam sensor.. But for reference the Black connector is C1, the White is C2, and the Gray is C3... The Cranshaft sensor plugs in on the back side of the passensger side of engine...
That is correct.. Here is pic
OK - I do see that - and I can see the wires come from there (3 wire connector) up the drivers side to a plug.
It may be routed a different way... Try and locate the sensor and follow the wires to the plug.. Here is another pic of where it maybe
ASD (Auto-Shut down Relay) its the Relay that the fuse powers up.. Also I really would like to confirm the fuse we are working on.. The lid doesnt have a number on it.. Underside or topside?
There is no numbers at all - Even the owners manual doesn't help! Its the only 30amp mini fuse and its right next to a 20amp mini -
would picture help?
Here is a picture
OK - mine is different - the upstream o2 sensor you can follow up to hard plastic encased square harness that runs along the fuel dist bar - the second downstream sensor runs up to a larger harness that come up behind the rear of the engine on the passenger side.
All the wire harnesses (plastic tubing looks to be in excellent shape from the senor to their terminous as descrbed.
No - I can turn the ignition on - just before crank and it doesn't blow. As soon as I crank the starter - the fuse blows.
When I tested pin 87 to ground - I think I had the blown fuse still the fuse panel - should I have replaced the fuse - and then tested?
Yes - I've disconnected all those items and I'm still blew the fuse in the exactly the same fashion.
Do you want me to disconnect all those items at once and then test pin 87 to ground?
EVen though my ohm meter sounded the alarm - I did stillmeasure about 3-4 ohms of resistence - it did not go to zero (pin 87)...
OK - with everything disconnected - there is no continuity between ground and my pin 5 (pin 87).
As I reconnect everthing - there is no continuity until I bring the o2 sensors on. Once they are plugged in - I get continuity...
I doesn't matter which either or...or both connected cause continuity between the asd pin 5 and ground...
What does that mean?
Yes - that is correct - just did - car started...But this is basically the same test I did first when we started this...I've already blown a fuse with both o2 sensors disconneced...
So now what???
kinda makin me think the sensors are OK - and there is a bare wire somewhere finding ground between the sensor plug and the pdc?
You dont have any continuity until you connect the O2 sensors..But the fuse still blows when you start vehicle with them disconnected.. Well If it was the O2 wires it would have continuity when they was disconnected.. Did you try and wiggle the wires when it was disconnected to see if the beep came back.. When you start the vehicle the shaking may allow the bare wires(if any) to touch ground.. And that is exactly what Im finding when I do a search for fuse 20 blowing.. So we may be onto something if we can trace it down... I will reply faster now that Im at home.. And by the way you have been doing an excellent job in testing this with me today..
I had continuity with them connected. No continuity with them disconnected. The car did start and I did not blow the fuse (this afternoon).
But I know this was the first test I ran this morning...BUT...I may have used a 20amp fuse instead of the 30amp fuse this morning...Reason being is I'm an hour from the auto store and I had only one 30amp fuse left AND I had started the car a couple weeks ago on 20amp fuse after blowing the first 30amp when the problem first arose...The 20 amp lasted long enough to get back forth from the autoparts store and then it was replaced with a 30 -which blew a day later...while driving - then the next 30 lasted a week...It wasn't until last night pulling a tractor out of a brush fire that the fuse blew again (yea - great timing)...It didn't restart till this afternoon.
Im glad it didnt get burnt up in the fire. But when you tested the Ohm's did you notice if one of the O2's were closer to .001Ω because a perfect wire is .001Ω and it one O2 is .167 and the other is .001-.050 then its shorted to ground.... I scrolled above and you did mention that you tested 3-4 Ω.. Was that with both O2's connected?
Lets test each one and see if they are different readings.. And test on Pin 5 at ASD relay..
Also when you wife arrives, disconnect both and wiggle the entire harness to see if you get a "Beep"...
We are getting closer, but need to narrow it down more... And when you say that is lasts longer with a 30AMP fuse than it does with a 20Amp.. That makes me think we are dealing with a high resistance circuit, rather than a shorted circuit.. If you understand what im saying...
Test that and post back results..
OK - here's what we found:
Rear o2 sensor cable plug to engine seems ok - no matter how I twist it - it does not send pin 5 to ground. Connecting it does.
The front o2 sensor - same deal but this one changes. When its connected - it goes to ground - but sometimes not - most of the time its at ground - I can twist and pull it and change it - but cannot keep it from making cont with ground. So while I rested under the car - with it plugged in - it just stopped - the ohm meter stopped the beep...witht the sensor plugged in - then I couldn't get it to start beeping again. Then I unplugged it - no change - then plugged it back in and it started beeping again.
I don't think this is any new information - thats just damn weird....
What? That is kinda wierd.. But with that and earlier you said that with the O2 unplugged it still blew the fuse.. Im feeling that its wiring.. But finding it will be having to tear out the wiring and inspecting it all the way to the PDC....
Yea - I've been working on since my last post...I've traced the leads as far as I dare not making any change to the continuity - I've wiggled and pulled every harness, lead and connector into which the o2 sensors are connected and nothing but continuous continuity to ground on node 5 of that relay.
Have not gotten back to no continuity unless BOTH 02 sensors are unplugged.
I lifted out the pdc so that I could wiggle all those wires into the pdc and still no confirmed change (that was tough with ohm meter stuck into the node)..
Is it worth knowing what the wire colors on the 02 sensor mean? There are 4 - two white one grey and one black - gonna guess sensor, heater, and maybe two separate grounds? What heats the o2 sensor??? That would be hight resistence I imagine...
I don't know...
Any other suggestions????
I would say its the O2 sensors, (IF) you could run the vehicle fine with them unplugged and the fuse not blow..And you cannot as you tested earlier... Next: When you tested earlier and you pulled and changed the beep, that sounds like wiring.. And for your O2 wiring, I will give you a little info:
On your O2 is 4 wire, that lets you know that its a heated O2 sensor and not a old 1 wire, There are 4 wires.. 1 gray, 1 black and 2 white.. The 2 white are the O2 sensor heater, one is 12v and the other is ground(It doesnt matter which way you hook them up), and the Gray is sensor ground and the black is O2 signal.. The newer O2 sensors have heaters to hurry and get them to 600 Deg, (WHY) because that is when they start producing voltage... Yes I said producing voltage.. They have zirconium in them, which usually produce a max voltage of .09v.. When the vehicle is rich(to much fuel) voltage is high, and lean signal is low voltage..The PCM uses this info to adjust the Pulse width of the injectors to get the best engine performance and less emissions..Ok, enough of the O2'sWell it would be nice if you could get the wires to act up... But it seems like they are not going to.. And when it still blew the fuse with them unplugged points at the wiring or something else causing this issue..I didnt ask,, but was the check engine light ever on.. If so do you know what the codes were?
The only time the CE light came on the car died at 40mph (yep - the fuse blew) and one error code was produced (twice) P0201
I assumed the misfire was caused by the fuse blowing with the vehicle under power...
So whats next - replace both O2 sensors?
Yep - will do - I had to get into the office today so I'll check that this evening...also plan to buy two new 02 sensors and plug them in (without install) to see if it creates the short - then maybe touch the nut threads to the muffler to see if that creates the short too...
Its hard to understand how plugging them in completes the circuit to ground somewhere unless the sensor itself is causing the short to ground - but why both and why no rich/lean error codes???...I can't answer...