Technical Intermittent No Start

[bugsymike]

Well, the Jeep dealer has the Renegade now. They said 3-5 days for their diagnostics. At least we have a spare car so we're good for now.
Strangely as I pulled into the service department I got a CEL
P0571 and U1408 which are both related to the brakes. So... hopefully it's as simple as a switch or a relay or something not engaging and the ECU not knowing whether the brake is being pressed to start the engine.

Either that or it's unrelated and just telling me I borked the brake switch replacement

I suppose now the problem is how long and how much for the dealer to correctly diagnose and fix it. Fingers crossed.

 

[DetergentCandy]

I suppose now the problem is how long and how much for the dealer to correctly diagnose and fix it. Fingers crossed.

Got my answer! Or at least a solution to move forward. They want to replace the brake switch with an actual Mopar part. I had replaced it already when diagnosing myself but it's definitely possible it just doesn't like aftermarket switches. But, this should also rule out oxidized contacts (@Mike1alike) AND tell me if there's still another underlying issue. I'll have 90 days to bring it back (and not pay the service fee again) if it's still having starting issues after they do the switch. And considering it was having issues just about every day, or every other day, it shouldn't take long to find out if it was indeed the switch.

 

[DetergentCandy]

Okay, overdue UPDATE!

I've been out of town for 2 weeks, but the Renegade is back in our possession and all is good!
Would you believe me if I told you it was a fuse?

It was still having starting issues after they replaced the brake switch.

Turns out the starter relay fuse had a partial break on one side (bottom left).

So while it wasn't broken enough to prevent a good current flow test or for it to start "sometimes", it was enough of a break to not start other times. Could have been temperature dependent, or it could have just been entirely random when current was able to flow through. Either way, it's been starting fine the last 2 days so that seems to have fixed it!

I'll have to remember to actually perform a good physical inspection of fuses next time rather than relying entirely on a meter.

I really appreciate everyone's comments and suggestions! Y'all have a lot of good knowledge here.

 

[bugsymike]

Okay, overdue UPDATE!

I've been out of town for 2 weeks, but the Renegade is back in our possession and all is good!
Would you believe me if I told you it was a fuse?

It was still having starting issues after they replaced the brake switch.

Turns out the starter relay fuse had a partial break on one side (bottom left).
View attachment 484728


So while it wasn't broken enough to prevent a good current flow test or for it to start "sometimes", it was enough of a break to not start other times. Could have been temperature dependent, or it could have just been entirely random when current was able to flow through. Either way, it's been starting fine the last 2 days so that seems to have fixed it!

I'll have to remember to actually perform a good physical inspection of fuses next time rather than relying entirely on a meter.

I really appreciate everyone's comments and suggestions! Y'all have a lot of good knowledge here.

That is good news. I have often checked fuses with a ohm meter across both sides.
Less of a problem in the old days with brass fuses, but aluminium ones, either corrode or crack.
A few years ago I bought an SIP 50/500amp industrial battery charger with jump start 500amp capability very cheap, at the time new it would have been several hundreds of £s, that was just the 50amp charging fuse cracked but looked intact.

 

[Ralf S.]

Okay, overdue UPDATE!

I've been out of town for 2 weeks, but the Renegade is back in our possession and all is good!
Would you believe me if I told you it was a fuse?

It was still having starting issues after they replaced the brake switch.

Turns out the starter relay fuse had a partial break on one side (bottom left).
View attachment 484728


So while it wasn't broken enough to prevent a good current flow test or for it to start "sometimes", it was enough of a break to not start other times. Could have been temperature dependent, or it could have just been entirely random when current was able to flow through. Either way, it's been starting fine the last 2 days so that seems to have fixed it!

I'll have to remember to actually perform a good physical inspection of fuses next time rather than relying entirely on a meter.

I really appreciate everyone's comments and suggestions! Y'all have a lot of good knowledge here.

That's really annoying.... I hate it when you get so close and then it needs the dealer to find it hiding in plain sight...

At least all your diagnostics had eliminated a lot of other stuff already, so it saved a fair bit of money, I reckon.



Ralf S.

 

[s130]

Looks like possibly that post and nut mount fuse could have been over tightened. The clockwise rotation and friction tearing the botton corner.

I'll have to remember this myself and if fitting such a fuse myself consider using a washer as well.

 

[DetergentCandy]

That is good news. I have often checked fuses with a ohm meter across both sides.

To be fair, I don't think anyone would have thought otherwise since that's the common "fool proof" way of checking a fuse. I guess it's not fool proof all the time

That's really annoying.... I hate it when you get so close and then it needs the dealer to find it hiding in plain sight...

At least all your diagnostics had eliminated a lot of other stuff already, so it saved a fair bit of money, I reckon.



Ralf S.

Yeah, it wasn't too bad. I still ended up paying about $600 after it was all said and done. But I'll happily take that considering I would probably STILL be chasing the problem today if I hadn't taken it to the dealer. So yeah, it was well spent.

Looks like possibly that post and nut mount fuse could have been over tightened. The clockwise rotation and friction tearing the botton corner.

I'll have to remember this myself and if fitting such a fuse myself consider using a washer as well.

That's honestly a great observation. I think I'm gonna do the same!