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KJ in limp mode. (aka: who wants to come on by for an automotive bonfire?)


Pete M
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the mode where it functions normally-ish but tops out around 3200 rpm whether in gear ir neutral. sounds/feels fine and drove all the way to attica so i'll be wheeling it tomorrow, but this is irritating.  the limp mode seems to correspond with the brake (!) light that came after I was trying in vain the fix the abs system the other day. 

thoughts?  i've got very limited cell coverage do I can't properly research anything today. maybe in the morning I can stab at stuff before we all meet up.

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I did some reading and it seems that limp mode will not reset if the code/fault is still present. 

 

These are the three ways I could find to reset your codes without a scan tool:

- unhook the battery for an hour or more

- touch your ground wire to the positive terminal of the battery to drain capacitors

- turn key on and unhook battery for 5 mins. 

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I'm assuming from the limited info provided-

 

ABS sensor or module threw a hard code to the ECU, ECU responded and went to limp.

 

Without a bidirectional scan tool you cannot read nor reset ABS. 

 

Unless fault is corrected with ABS you will not be able to reset ECU. 

 

If ABS fault is not resolved, a dealer may be able to reset ABS and clear faults, however, the cycle will repeat and you'll be right back to where you are now in a couple of days. 

 

ABS will need to be serviced, ABS module will need to relearn, ECU cleared. And you'll need access to bidirectional tool.

Either way it's going to be expensive. 

 

 

If it were me, I'd strip out all ABS, have ECU cleared. My question before I attempted- Will ECU need input from ABS module to function? IOWs will ECU search for ABS and if not found will it automatically go to limp? This needs an answer. 

 

I alluded to all this in my rant regarding my Nissan, as I said then, people don't really understand how this $#!& works. 

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Deleting abs from a CRD is possible and requires the DTC table to be modified to delete the abs code. 

 

Pete, seems like a guessing game without reading any codes. 

 

Are you sure you are having no air in fuel issues?

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ok, I'm back in michigan and have some wifi. :D    

 

to expand on the first post, the ABS/tractioncontrol/cruise has been out for years now (with the lights on the dash).  I prefer the abs to be gone, but I do miss cruise control so last week I did some testing just for the hell of it and I unplugged the abs computer in order to check continuity in the sensor wires (seems I have a break in the pass/rear).  that was it though.  just unplugged it and plugged it back in, that's it (that I know of at least).  fuses are fine.  She drives fine and idles fine and everything seems fine until you ask it for higher rpms.  I have the upgraded fuel filter head and it hasn't hiccuped or anything.

 

When it comes to codes, a trip to the dealership is always required with this Jeep. :(  and if I remember right, last time I had to go to a specific dealership with the big scanner.  I'll be getting codes later this week and will update.  

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I have an older Actron that reads codes on all my Jeeps, from the 91 MJ OBD1 system to the 2018 Compass. I have to update the software for the newer OBD2 models sometimes to keep up, but it's supposedly compatible with all current OBD2 vehicles. Hasn't failed on any vehicle I've tried it on, including some OBD1 vehicles that may require a special cable to fit the varied diagnostic connectors.

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On 8/26/2018 at 5:51 PM, Pete M said:

link?  I'd love to have a reader that can pull codes from this Jeep.  :D  

 

This one works well for all the modules on the CRD:

https://www.amazon.com/gp/product/B0090B7M2O/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

My $50 harbor frieght unit also works fine on the CRD.

 

My $20 wifi code reader also works fine.

 

 

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a harbor freight unit will pull codes? :eek:  the last time I was at a dealership for codes they had to break out an uber expensive reader to do it.  :dunno:  I may have to run to HF tomorrow and, um, "try out" their reader.  

 

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10 hours ago, Pete M said:

a harbor freight unit will pull codes? :eek:  the last time I was at a dealership for codes they had to break out an uber expensive reader to do it.  :dunno:  I may have to run to HF tomorrow and, um, "try out" their reader.  

 

Dealer readers cost $10-12K and cost about $1K to update annually. A dealer may have 12 techs and 2 readers, apparently it's a common complaint that there is always someone waiting on a reader. 

 

I would love to have one myself, I don't know anyone who has a deep reader that I can get my hands on. Some time ago I found one that looked interesting for about $400, tablet style and is bluetooth, was not tethered to the dash, for the life of me I cannot remember the brand and I cannot find it again. 

 

Spending $400 to $500 on a tool is a major investment for me.

 

A cheap reader that reads beyond OBDII may give you a generic wheel sensor code but if it cannot narrow it down to a specific wheel, give values (data) in real time, what good is it? If it cannot register or 'marry' sensors and modules, what good is it? You're off to the dealer anyway. 

 

And when you will be spending $500 to $1500 for a sensor or module.........you had better know what you're doing because the dealer is not going to warranty your mistake. 

 

One of these days I'll buy one. For certain the next generation of hot rodders..........a laptop will be their first tool.

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success! :banana:  I think.  well, so far for the test drive at least.  later today I'm driving an hour up to my cousin's place so that'll be the real test.  

 

both rear ABS sensors show issues so I think I'll just go ahead and replace both lines in their entirety.  

 

found a low fuel pressure code but that might be left over from the issues with the fuel filter head.  I cleared it and it hasn't come back (yet).

 

all in all it was worth the money just to not give that money to the dealership. :D   

 

thanks everyone! :beerchug:  I'll update as events warrant.  

 

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4 hours ago, Jeep Driver said:

Dealer readers cost $10-12K and cost about $1K to update annually. A dealer may have 12 techs and 2 readers, apparently it's a common complaint that there is always someone waiting on a reader. 

 

I would love to have one myself, I don't know anyone who has a deep reader that I can get my hands on. Some time ago I found one that looked interesting for about $400, tablet style and is bluetooth, was not tethered to the dash, for the life of me I cannot remember the brand and I cannot find it again. 

 

Spending $400 to $500 on a tool is a major investment for me.

 

A cheap reader that reads beyond OBDII may give you a generic wheel sensor code but if it cannot narrow it down to a specific wheel, give values (data) in real time, what good is it? If it cannot register or 'marry' sensors and modules, what good is it? You're off to the dealer anyway. 

 

And when you will be spending $500 to $1500 for a sensor or module.........you had better know what you're doing because the dealer is not going to warranty your mistake. 

 

One of these days I'll buy one. For certain the next generation of hot rodders..........a laptop will be their first tool.

 

The autel I posted will read, trend, and save live data from all the sensors, including all 3 or 4 wheel speed sensors. 

 

It also reads from all the little modules like the ocm, rain sensor, etc. 

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Failure!  seems my jubilation was premature. :doh:  worked great for the test drive but last night it fell on its face again.  codes all came back too.

 

codes of note include:

p1186 fuel pressure minimum pressure at engine speed too low

U0002 CAN C Bus off performance

 

is this then the indicator for needing a lift pump?  

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4 hours ago, Pete M said:

so far this plan is in the lead:  http://liberty.eurekaboy.com/kennedy.htm  but using a Facet 40109 pump.  

 

Pete the fuel filter is a good place to start, but I would really recommend the cummins in tank lift pump and modified OEM wiring harness. Aint nothing like a clean OEM install other than using OEM parts and making it like it should have been from the factory.

 

You need cummins lift pump and some wires to add your your existing harness.

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I completely agree, but that's just not in the budget at the moment.  :(  I more or less need to try something to get it drive-able again and later on we can do the whole shebang when I take her off the road for a while to do the suspension fixes and get the cruise working again.  

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when it rains it pours, right? :(   so the alternator now refuses to charge the battery.  fan-freaking-tastic.  :fistshake1: 

and so I shall start researching this one too.  hope I can find a writeup for testing if it's the clutch.  that sounds like it'd be cheaper to replace. 

 

the silver lining is that the alternator is riiiight up at the top and easy to get at. :D  

 

the other silver lining is that I learned this while driving to a friends house rather than the middle of detroit if I had bought that truck box, or halfway through ohio when I go back south in 2 weeks.

 

so I guess step one is pulling it and running to autozone.  orrrrrrr wait til tomorrow when the temp is supposed to drop like 20 degrees...  hmmmmm.....  

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so I've learned that Chrysler alternators need to be in the jeep in order for them to test them. :doh: good to know.  I also am wondering how the brick-n-mortar stores stay in business since I can order a alternator from autozone's own website at 20% off the store price and have it at my doorstep in the morning for free.  :dunno:

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