Check engine light comes on when I turn on bed lights????

[Gladiator Brad 704]

Codes the dealer resd are: B156D-00, UO485-00

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[HooliganActual]

The bed lights do come on and off as they should. The insturment cluster was replaced under warranty about 6 months ago. It went totaly black. I seldom use the fog lights and probbly havent used them since the replacement of the cluster. I am sure in the past the engine light did not come on with the previous cluster. I do not get the light symbol posted by TestMule.

I will get the code read asap.

I'm now also doubting there will be a code. Seems like something went wrong with the cluster replacement. I'd be interested to know if a DTC would cause the bed lights indicator to go on ?

As a guy who used to travel around my company for 20 years performing Root Cause Analysis on machine failures, I totally subscribe to a principle known as Occam's Razor (essentially, the simplest solution is usually the best).

The first two questions I would ask the teams I was working with were 1) when was the last time it was known to be working correctly and 2) what maintenance was done between that time and the failure.

Personally, I think you have told us what is wrong...the instrument cluster replacement. If the CEL comes on when you turn the bed lights on but the bed light indicator does not, I would wager that the wiring for the the two lights is switched around. I don't know if that is one harness plug that may have pins incorrectly wired or if there are separate wires to each light (I'm sure someone here will know) but that is honestly where I would start my diagnosis.

I mean, turn bed lights on, CEL light comes on; turn them off, CEL goes off. No codes indicating engine issue. Sounds like somehow the bed light indicator got crossed with the CEL during the instrument cluster replacement...

EDIT: the two codes you gave are related to radio/video harness issues which again may be related to the cluster replacement...

 

[Gladiator Brad 704]

I forgot to mention, when I open the door the check engine light also comes on. Running or not. In drive or park.

How can I comunicate with the service tech. at the dealership? I don't want them tearing my truck apart looking for chafed wires that are not there. I think they should start with another cluster replacement, ( it took almost 5 months to get the first replacement cluster ). Do you think they will eaven have a clue as to what Occam's Razor is? I do not. They have always totaly disreguarded anything I have to say. I used my free oil changes with much trepidation. The oil changes included a free tire rotation. When I started changing my own oil and rotating the tires myself I found the lug nuts to be severly over toqured. I had to use a 4' breaker bar that I have for my tractor to get some of them off. If I had been on the side of the road I would have been out of luck. Looking foward to your advice.

 

[HooliganActual]

I forgot to mention, when I open the door the check engine light also comes on. Running or not. In drive or park.

How can I comunicate with the service tech. at the dealership? I don't want them tearing my truck apart looking for chafed wires that are not there. I think they should start with another cluster replacement, ( it took almost 5 months to get the first replacement cluster ). Do you think they will eaven have a clue as to what Occam's Razor is? I do not. They have always totaly disreguarded anything I have to say.... Looking foward to your advice.

I can’t even guess how to get the dealership to think like me; however, every time I have been to a dealership in 40+ years of car ownership, even the crappy service teams ask me "what seems to be the problem?" Just take it in and tell them "Hey, you guys replaced my instrument cluster on "X date" and now these things happen." Then show them the CEL when the bed light is turned on and the CEL when the door gets opened. You're actually in a better place than many others are with the issues they have because they can't "reproduce" the symptoms when they bring the vehicle in.

If you have no faith in that dealership, is there a different one you can go to? I have bought my 2 JKUR's and my JTR from a dealership that is about a mile from my house but their service team are jackwagons. I drive 10 miles to a different dealership that has a crappy sales team but an awesome service team. You have the right to take that vehicle to a different dealership.

It costs you nothing except your time and effort to at least see how they (or another dealership) will listen and approach the issue. HOWEVER, if this has truly been happening since the cluster replacement, you need to insist that it is related. Now it might be that some other harness (like others here have suggested) got damaged in that replacement but make that case.

I'm a retired Reliability Engineer and many studies have been done over the last 50 years that have literally proven that 60+% of failures (20 year long case studies of military and civilian aircraft) are typically related to work that was just performed, things like:
1) installing a defective part (harness wired incorrectly) which fails shortly thereafter
2) installing said part incorrectly (think forgetting to grease a bearing at install or overtorquing stock lug nuts and damaging the outer sheath)
3) damaging a different part during the repair (there's tons of threads here where someone drilled through a wiring harness while doing an install of something else)

Go in informed and be insistent that it can't be conicidental and they must be somehow related:
1) Dash cluster replaced on "X date"
2) CEL goes on/off when bed lights turned on/off
3) CEL goes on/off when door is opened/closed
4) B156D-00: The Display Screen Module (DSM) detects that the Low Voltage Differential Signal (LVDS) Video Cable is disconnected for greater than 10 seconds

a) Service Bulletin: S1908000097 https://static.nhtsa.gov/odi/tsbs/2020/MC-10177484-9999.pdf​

5) U0485: Implausible Data Received From Radio

a) Service Bulletin: S1908000097 https://static.nhtsa.gov/odi/tsbs/2020/MC-10177484-9999.pdf​

​

If they don't want to hear you, take it somewhere else. I've even found that different Service Advisors act differently, so don't talk to your regular person.

Give it a shot

 

[sharpsicle]

I forgot to mention, when I open the door the check engine light also comes on. Running or not. In drive or park.

How can I comunicate with the service tech. at the dealership? I don't want them tearing my truck apart looking for chafed wires that are not there. I think they should start with another cluster replacement, ( it took almost 5 months to get the first replacement cluster ). Do you think they will eaven have a clue as to what Occam's Razor is? I do not. They have always totaly disreguarded anything I have to say. I used my free oil changes with much trepidation. The oil changes included a free tire rotation. When I started changing my own oil and rotating the tires myself I found the lug nuts to be severly over toqured. I had to use a 4' breaker bar that I have for my tractor to get some of them off. If I had been on the side of the road I would have been out of luck. Looking foward to your advice.

The thing with warranty work is neither you nor them get to really choose what steps to take. You do your best to show them the problem, maybe nudge a little bit, but then you need to leave them to their work. They investigate the issue and then follow procedures for additional troubleshooting and testing. If they want to verify the integrity of the vehicle harnesses, why stop them? Who knows, there might actually be a problem there. It's usually counter-productive to try and restrict troubleshooting.

Just because I said I think something went wrong with the cluster swap, does not mean that is the problem or that it's be best place to start. Let them work to eliminate possibilities, it's their job.

 

[Gladiator Brad 704]

Great advice! I have an appointment on 9/19/2023 09:30. The links to the service bulletins are informative but I have had no problem with my radio. The service writer said it is likely the battery. I told him that I completely disagree. Then he backed up and said the tech. would be able to do more diagnostics on 9/19. Just don't want these guys taking a small problem and turning it into a big one. Will keep you all posted.

Also this dealership has just been sold to a new owner and i didn't recognize anyone in the service dept. I do have an extended warranty that is still in effect. I just wish I could watch what the tech. does. I love my Jeep and don't want to get rid of it over a problem like this.

 

[HooliganActual]

…but I have had no problem with my radio…

Right, but you said those were the two codes that were read. I was only arming you with information related to those two codes. Ultimately, you have two codes related to items in the dash and wonky lights in the dash and the dash was recently worked on. That’s not coincidental.

Good luck on the 19th.

 

[Hootbro]

I forgot to mention, when I open the door the check engine light also comes on. Running or not. In drive or park.

That is because the bed lights normally come on as part of the door open lighting scheme

I think a good data point would be to pull the F97 radio fuse and see if the discrepant condition still exists. If it is still there when you pull the fuse, radio is low probability in my opinion.

Pulling the F97 fuse though may cause the radio to go into a factory default reset with limited function and will probably need a deep sleep reboot which is engine off, doors locked and left for a few hours before it reconfigures. May have to do it twice.

 

[Gladiator Brad 704]

I will go pull the fuse now. Will report back soon.

 

[Gladiator Brad 704]

With F97 fuse out, situation still exist.

 

[Hootbro]

With F97 fuse out, situation still exist.

I think the radio codes are a red herring then. They would not normally drive a check engine light and are a latent code statusing the radio module.

Like @sharpsicle mentioned, let the dealership work their process. That replacement cluster is looking more and more suspect to me.

 

[ShadowsPapa]

As a guy who used to travel around my company for 20 years performing Root Cause Analysis on machine failures, I totally subscribe to a principle known as Occam's Razor (essentially, the simplest solution is usually the best).

The first two questions I would ask the teams I was working with were 1) when was the last time it was known to be working correctly and 2) what maintenance was done between that time and the failure.

Personally, I think you have told us what is wrong...the instrument cluster replacement. If the CEL comes on when you turn the bed lights on but the bed light indicator does not, I would wager that the wiring for the the two lights is switched around. I don't know if that is one harness plug that may have pins incorrectly wired or if there are separate wires to each light (I'm sure someone here will know) but that is honestly where I would start my diagnosis.

I mean, turn bed lights on, CEL light comes on; turn them off, CEL goes off. No codes indicating engine issue. Sounds like somehow the bed light indicator got crossed with the CEL during the instrument cluster replacement...

EDIT: the two codes you gave are related to radio/video harness issues which again may be related to the cluster replacement...

For me, I simplify it to "what changed" when troubleshooting. If there was no human interaction then much more simple troubleshooting techniques can be applied.
If there was human interaction with the device having issues, it often complicates things as extraordinary problems can be introduced where they'd never normally or naturally happen.
Swapped out printed circuit on the back of the cluster for my car after swapping tachometers and doing some repairs. Put it back in, temp gauge didn't work. Fuel gauge did so it wasn't the IVR.
OK, what did I have my hands on - oh, the 4 nuts that secure the printed circuit to the temperature gauge. Sure enough, one wasn't snug. It worked before - (and others on the same power supply did work) so what changed.........

 

[ShadowsPapa]

I'm a retired Reliability Engineer and many studies have been done over the last 50 years that have literally proven that 60+% of failures (20 year long case studies of military and civilian aircraft) are typically related to work that was just performed, things like:
1) installing a defective part (harness wired incorrectly) which fails shortly thereafter
2) installing said part incorrectly (think forgetting to grease a bearing at install or overtorquing stock lug nuts and damaging the outer sheath)
3) damaging a different part during the repair (there's tons of threads here where someone drilled through a wiring harness while doing an install of something else)

You may enjoy this story - it's more QA or "inspection and testing" related but similar ....
A friend of mine who used to live and work near Chicago worked in a company that made electric and electronic parts for cars - companies like Toyota. They made a specific relay.
The testing was to consist of 10 iterations of a test and if it failed one time, reject it.
Toyota came into the plant complaining of a high failure rate on that part. The company looked into it and traced things back as far as the testing.
The guy running the testing was checking each part by test it 10 times and if you can get it to work even a couple of times out of that 10, it must be ok.
We were rolling when Ron told us of that. Seriously? If you can get it to work it must be ok?

 

[HooliganActual]

@ShadowsPapa

I’ve had so many like that. My all time favorite one was going to a plant that was having major issues with an overhead bottle conveyor; it was in fact the #1 cause of downtime for the facility as the bottles would get stuck and back up the line. This style of conveyor actually holds the bottle by the neck and it moved along rails by air blowers.

When I arrived, they showed me this conveyor that was about a foot above a fork truck passage door that moved from one warehouse to the next. They told me that a fork truck with its load too high hit the conveyor and bent the airveyor all cattywampus.
Me: “Seems simple enough, replace that section of conveyor.”
Them: “Well…we have all the parts, but it got hit again last week before we could replace it and now it’s better. It dropped to #5 on the downtime list now”
Me: “What’s #1 now?”
Them: “The Line 3 Palletizer”
Me: “Let’s go hit that with a fork truck!!!”

 

[Gladiator Brad 704]

At the dealer now. The service tech. says there is a recall on some guage clusters he is checking now. Anyone heard of this?

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