Replaced my heater core and was having all sorts of weird electrical stuff when I tested it before buttoning everything up. Turning on the heater fan turned on the dash high beam and turn signal indicators. The blower fan would only engage when I turned the interior dome lights on. I ripped out all sorts of stuff and spent 3 days hunting with my multimeter for a short. One time I had the entire heating system working until I slid the dash back in, only to have my problem return. Finally stumbled onto this video on a forum and had the same solution. Thanks for posting! Who knows how long I would have been hunting. 😊

Cannot let "Shoulda coulda woulda" cut into earnings, at least you found it when nobody else did.

I find that nearly every time when something very very strange is going on - GROUND is that guilty one!

IT'S THE GOVERNMENT! Awesome call Eric O.

I keep coming back to this video just to hear Eric say "It is the government", when he is looking at the circuit board in the dome light assembly. LOL

Great ending, (almost) nothing better than riding in the woods after a stressful day with a good friend.

Gotta say, this video reminded me of the scene in Apollo 13 where they are trying to restart the ship without going over current. LOL

Given that that "mystery board" is: high in the vehicle, has close proximity to the dome light, has a relay, logic chips, has a bus-com= I'm *_guessing_* that module is the *RKE*. As with my '89 Reatta- the *RKE* switches on the courtesy lamps, illuminates the odometer. Lifting a door handle does the same. When locked- tripping the alarm flashes the fog and tail lamps, sounds the horns, and disables the ignition. Yes- an '89 Buick with alarm and RKE from factory.

nice one! From the second you pulled the head light switch I was telling my self check the GROUNDS.ive had several trucks that stall or run rough when turning on head lights,and it's always always a ground issue somewhere and once even the headlight switch causing a current back feed through the pcm trying to find a ground. Awesome you guys found it.

It's this kind of crap (lose earth bolt!) that makes me all sentimental about my first car a mk1 escort. The only electronics it had was my Casio calculator watch in the glove box.

Thanks guys. You two hobby boys together. Lots of fun.

Awesome to see two master mechanic at work!!!!!

Absolutely unbelievable. Love fixes like this.

Maybe Eric should hire you ! FYI Biasing a twisted pair comm link IS somewhat common. Helps "noise immunity" by "lifting" the signal above the noise, which is typically between 0-1V.

Too smart guys having fun together, teaching us some valuable lessons about checking powers and grounds! Happy new year.

Nice find guys. Always simple once you find the problem.

The board up in the courtesy light might be the delay/fade function for the lights,or some "Retained Accessory Power" thing. Just a wild guess.

i really enjoy these SMA spin-offs :)

Eric O in spandex? Awesome. Looking forward to another year of entertainment from you all. Great video Ivan, love your channel

Great job guys.

Man that was a good episode, you guys have the patience of saints. I was thinking of creative ways to destroy the damn thing and put it out of it's misery, while I was watching the video! What a piece. Another lesson of checking the basics and not jumping the gun with swap-troniks, thanks!

I would've called Father Karras right from the start!!!! What a mess!! Great vid Ivan, hope you guys have had the best of holidays!!

Nice work guys and good find on the loose ground. Nice snow that you guys were having up there. Take care Ivan and Eric...

Nice troubleshooting especially when you know it loses it's ground when the circuit is loaded, you just have to find it and that's when it gets fun. There's nothing more rewarding then having a problem others have tried to fix and getting to the root cause and a solid fix! Great to see you and Eric working together again and then having some fun mountain biking. Looking forward to more great videos in 2016...

That logic board is part of the keyless entry system, but you've probably figured that out already.

happy new year to you and your family, great team work

nice fix guys hard to think just a loose bolt caused all the problems. happy new year to you all cheers

Great video, even though it turned out to a basic repair, there is nothing more rewarding than fixing something that others couldn't, I really enjoy your videos, and it's awesome seeing the two of you working together.

That was another Great video, the part about Government was something my wife would have said. Enjoyed it very much!

Awesome video

great videos!!

great find man, ground problems are tricky

Thank you both for the expertise you are willing to share with us via your fascinating videos . I for one hope you maintain your enthusiasm and dedication for these. The professionalism you demonstrate is truely exceptional. Happy New Year to you both. Alan B.

Nice job guys. I was guessing that the cluster was back feeding. Ivan you sure burst my bubble when disconnecting the cluster had no effect.......LoL. I was thinking all sorts of goofy shit til I watched the video for a second time. As soon as Eric started poking around it all started making sense. Thank you for the fine entertainment.

You guys are good!

Hats off to you, not many guys would Have found that problem.

I added a overhead console to my XJ. It has a whole separate wiring harness you have to pull from the donor Jeep. They all plug into that box. The keyless entry is that little circuit board.

hey there ivan happy new year to u too...lookn forward to more of ur awesome diagnosis....DAM ur pretty sharp my friend.....great job....ur videos do and will help me out in the same field u do.....man u and eric make a great team together for sure for sure...haha....top guns...

That's by design. The bus also needs the headlights so it can see when it's dark outside right? lol Damn chrysler and their funky electrical systems. Guess it's job security though

Man made issues are the worst. This video gives me the motivation I need to build a high amp test light with a car headlight.

That is one COOL dog!

Hi, Ivan and Eric, this is a classic!!! Fabulus diagnose guys! In our damp country of the Netherlands (2/3 of the country below sea level!) its almost a daily bussines. taillights and blinkers all without a solid ground will ruin the electrical system.

Great video. Keep it up

Holy 2 craps a Friggen loose bolt. .... Damn!

Well, how many times do you fix an electrical problem with an impact driver....that was crazy! And I think I got a name for the two of you....The Green Crusties :D

Did that Jeep come from the Flintstones? Wow, what a mess. It's cool you guys work so well together. Eric is so busy I'm sure he appreciates the help. Awesome diagnostics.

Nice coat Erico and the end I have same one

Eric looks so cute in those pants at the end. Haha. Can't wait to see more mountain biking updates.

Things heard in Eric's SMA shop: "I just gave it the classic reach around move"... Yeah, that just happened. 31:12

Just incase y'all were curious. That "mystery board" y'all were talking about is for the keyless entry system on the 97-01 XJ's and to correct something you said earlier in the video about the XJ's being pre wired for the overhead console is incorrect, I added an OHC to my 2000 XJ and you have to have the OHC wiring harness that corresponds with the year of the XJ because they are completely different from the base non OHC harnesses. The only thing the XJ's had if they were not factory equipped with an OHC was that keyless entry board.

That jeep looks like King Kong and Godzilla had a party in it. Just watch out for those black helicopters.

I had a friend that put his ground for the 02 sensors on the alternator output, seeing it was a fish eye crimp end. It would stall sometimes and run rough after warming up. Dodge durango 5.2l. It took me a few hours to find out where I was getting power on the ground circuit for the heaters, since I unplugged all the fuses and power sources and still had power on the ground.

Its the man keepin an eye on you haha

Ahahahah the load pro would have failed just like i have been preaching , nice to hear you guys say that and very nice bikes , you guys kick ass .

O great fix looked like a ground problem

Looks like you guys need a LoadPro' ... I was working with a Mec" a few years ago that tested EVERYTHING with his LoadPro' he would (NOT) with out it! At the time I didn't understand why or really cared. But NOT any more!! I have one and use it EVERY TIME!! It has saved me sooooooooo much time and made me more and more money..

I have a friend with a 99 Cherokee, that had some strange gremlins. Turned out to be a ground cable from the negative battery cable at the terminal, going to the body beside the battery. With no hold down, the battery would move just a bit, and broke the terminal on the body connection. The cable was stiff enough to maintain a simple touch connection, but would sometimes not maintain that connection, and stupid crap would happen. Even when disconnecting the battery negative cable, the way the body ground was ran, it wouldn't show issues until I physically grabbed the cable at the body connector, and moved the wire away from the broken terminal. Once I replace the terminal on the body ground, all gremlins went away.

Looks like a job for a LoadPro-ProSelect: All the load you need where and when you need it.

my 97 Cherokee had a similar thing. Always wondered what it was for.

Just got to love those McGuyver repairs by backyard mechanics. The Vehicle was used by the Guverment Special Op team and that their secret GPS unit to report the location of the vehicle back to the NSA or Homeland Security. Probably because I used the term Homeland Security and NSA, in this post the Gurverment have you on their radar. LMAO Happy New Year!!!

Wow them floor pans are sweet. We see a lot of that up here in Michigan as well but are labor rate is higher so I don't think they would put that kind of money into it. That is a really custom jeep there and Erics jeep hat must of not been working

That board is also the antenna for keyless entry on xl bodys

Great fix!!! Who'a thunk a loose dash bolt?

Glad Eric gives you the nice work!He must be mad at you.

That is Amazing, all that for a bad ground :-)

You guys work well together, enjoyed the video. Had a big laugh at "The Government". My question is: who's going to put that interior back together?

All the headache and swaptronics and reflash for a crusty, not fully tightened ground bolt. That's just (road) salt in the owner's wound. The circuit board in courtesy light may control the delayed dimming of it. But bcm might control that too. Just my guess.

Cool Eric and Ivan working together, quite the treat. Ivan I would say you just need to order a new mystery box 📦

Swerved right into that one, once in awhile we all get lucky

A few years back the radio on my 2000 would go out when I would use the power windows or the locks. Turns out the ground was bad for the radio. These things and their grounding issues

Got a love electrical

logic is to turn the dome light off after a period of time i guess or to light it when the remote unlocks the doors

just for your information, the bus based on two twisted wires is using lvds for transmit single

XJ Cherokee nerd here... CCD bus is sorta a Chrysler 80s almost-CAN bus. Not the same, but similar concept. If you need more info on it, check www.kolumbus.fi/~ks9292/CCD_bus/ccd_display.htm The board there is actually for the remote keyless entry system! It's the receiver. The crimps on that harness behind the instrument panel are probably from someone replacing the instrument panel connector. That connector on 97-01 XJ Cherokees is famous for causing "No Bus" error messages and dead gauges, a thump on the top of the dash will temporarily fix it and replacing the connector or retensioning and cleaning the pins will permanently fix it. The dealers actually have a TSB for that one, it's TSB 08-15-99. Here's more info on that. www.4wdmechanix.com/How-to-XJ-Cherokee-Erratic-Gauges-Fix?r=1 If you need any other info on diagnosing electrical issues on XJ Cherokees, let me know, I'm an electrical engineer and jeep enthusiast and have worked on a lot of them.

I’ve had something like that to in my 99 300M.

I love my Cherokees.

Well there's your problem!

Just Empty Every Pocket

On the right side of dash connector you were seeing current/voltage on the ground wire due to the ground not returning to ground? Why was this showing up on the bus wires? Gotta love loose grounds. I bought a car with a "Locked up bad engine", got it home and turns out the main ground that bolts to the frame in the trunk (battery in trunk) was not tightened all the way. Rethreaded the stud and good as new.

forget the loose groundbolt. whats with the dome light pcb. is it a mind control device!? i knew it. they want us to buy more skittles. what a coup.:-)

I agree with the dog

I had this same issue on my moms 1999 Durango.... Same bolt.. To me it looked like you loosen the bolts to pull the dash up in order to replace the heater core or something... But that loose bolt on her Durango had her heater controls ip lights flickering and blower motor going on and off.... So I'm assuming that bolt on each side of the dash is very important.. Lol

'99 is PCI Bus for Cluster??...Changed to CAN Bus with (EMIC) LIN Bus Master '07...?? Got me looking at Dome light to see if "Govt" still involved...Wait...I hear a helo.....

This ground reminds me of a Mini I drove.It worked grand in my locality, but as soon as I brought it to the big city, it cut out randomly all over the shop. There was no need for a treadmill that day.My other half was not impressed.The battery was in the back with what turned out was a dodgy earth.Great faultfinding skills to uncover that particular fault and good teamwork. In hindsight, would ye have approached the problem any differently than the way ye did.If so, what changes ?

Holy Crap. Think some one needs to make the call. Donate the Jeep to science or the local school shop class and write it off on the taxes.

I actually started laughing when you tightened the bolt and the gound kicked in ...shit!!!!!! Are you SURE the load pro wouldNOT have helped there??? I think I might send one to Eric or you so you can do some live field testing .... Damn that was tough one!!!

you boys must have each needed an extra large hot chocolate for sure and for certain!

Fantastic vid guys. One question- when checking com lines you used a body ground for the scope and not the dlc. ECM ground, would that have been helpful in determining a bad ground . Ah the mention of the Loadpro , man I wish you had one just to try out in this instance. 👍👍

that's a beautiful dog... you should make a vid just about him / her..

Got the same Garmin 500 with a strap.

Find the person who didn't tighten the bolt and sue them for the value of both PCMs and associated labour.

I can't find part 1, is it still posted?

Looks like my moms Jeep we have been working on for 3 years now trying to figure out why it won’t start..replaced everything now..some things twice...cranks beautifully but won’t start Look at the security system in it...it all started with the headlights setting off the security system which shut it down and won’t let it start..can’t get it to stop setting the security off either...putting the key in the ignition sets it off..the Jeep tech couldn’t figure it out but charged us $900 for an old used up pcm from a junkyard only to scratch his head and say he didn’t know

Ivan @ 3:50 when the instrument cluster rpm and vehicle speed was not working, why was the oil psi, fuel level, battery voltage and cooling temp working? Shouldn't those not be working since all of these gauges work by messages from the CCD bus? Also can you please do a video on how this missing ground can cause the high voltage on the CCD? Thank you Ivan

Good problem solving. Thanks for posting the video. Did you say you are on holiday? Eric saved this one for you, nice little present. Just kidding, it shows his confidence in you. BTW - I tried to find schematics for ECM on a 2013 Sierra on BBB Industries website without luck. I called Tech Support and he said they went from Mitchel to a new source and now you have to dig for somethings. Anyone know where to look on their site? Thanks in advance.

did eric hit you again,geez its hard to look tough when eric is waring tights

That stuff in next to the dome light is the keyless entry stuff.

I have a solution, works every time. First, get the title, second, drive to a junkyard, third, sell Heep, fourth, buy something else

Logic says unplug the cluster

I'm guessing the can bus line is getting pulled down by a short