Dude, thank you for the excellent diagnosis. I've been chasing electrical gremlins in my '01 Grand Cherokee for weeks. It all started with a no crank ,no start. Cleaned all grounds, new pcm ( which was fine for 3 days then left me stranded). I put the old pcm back, topped off the battery cells w/ a charge and no issues except for an occasional amp gauge waver from 13.5 to 14. 5 with all accessories on.

You must be busy because It’s been a little while. It is pretty simple when you know exactly what you’re talking about. You bring it down to a level everyone would be able to understand. Btw the intro is awesome brings me back to those days when they showed educational videos in school.

Never heard of a fuse tap. Genius idea man. Learn something everyday. Thanks for the tip. You Rock.

Excellent job teaching us microcontroller basics. I can see how lesser mechanics would start by replacing the ECU. If you pull all the sensors and you still don't have the 5v vcc needed, then check the 5v pin at the ECU connector. If you still don't have 5v, then open the ECU, look for a 3 pin part labeled 7805. This is the voltage regulator that takes 12v and outputs the 5v. If the 7805 regulator measures 12v and ground OK but no 5v, then desolder the 7805 and replace it. That should do it. Also, once all sensors and ECU are unplugged, you should have no reading across the gnd and 5v rails when measuring resistance. If you have any reading then you have a short in the harness. Good luck

Clicked like before even seeing video, know it's going to be interesting. Thanks Chris.

Thank you for the excellent video, solved my problem quickly, thanks again and again. Exactly what my problem was.

I want to say thank you because for 6 months I have been trying to understand what the problem was with my jeep and nobody I mean NOBODY explained it like you did and now I really understand what is wrong with my jeep! Thank you again and I subscribed to your channel because I know I will need you again someday!

Chris! Glad to see you back! Great video!

Great seeing you brother! Great case study as well! Missed you and your videos! Hope all is well! God bless!

Very helpful, thanks for posting this.

Dude! Glad to see you back here making videos. Thought about you the other day while diagnosing a head gasket failure on a CAT 307D. Was able to use a pulse sensor with relative compression to prove the failure, but wished I had a piezo tach pickup to use for sync. Hope all is going well in your world!

You sir, are a genius!

Thank you so much for this video!

Nice to see a video from you brother hope all is well. I have a 99 Jeep Wrangler no rpm , crank no start gotta love the early models putting a steel bolt in an aluminum transmission bell housing for crank sensor lol awesome those engineers. Good to see you brother

Excellent vid bro, I noticed on initial crank over no start there was no RPM function on the gauge, called crank sensor then haha

I subed just because you have a cool intro man thanks for the info

Very helpful. Thanks for sharing

I bought a 2002 grand cherokee 4.7 4x4 and had the exact problem....it was the camshaft sensor...thanks your video was alot of help

Great video 👍. Digging the new intro! Good to see you brother hope all is well.

Thanks for the info

This was a great video made it simple to understand I just did an engine swap on a 1999 jeep cherokee sport I have fuel cranks no spark or injector pulse dash says no bus any ideas

What an awesome video bro thank you!!!

Thank you sir‼️🙏🏻🙏🏻🙏🏻

Nice protocol

very good

What happens when you do exactly what you said. I unplugged every sensor and couldn't get the 5v on reference. Please help

I recently pressure washed my 4.7 right near the crank sensor and cam sensor, nothing on the top of the vehicle at all. Now I have no comms at all, SKIM/key light is on. I unplug the crank sensor and still have no comms, could I have water further down the wire loom shorting something out? I picked up a new crank sensor and in the process of installing that.

Great video, My 2001 grand cherokee has a no start/no crank. Can't figure it out. New ecu/battery, lasted 1 week then left me stranded again. No power.

Please looking for help. I have a 1993 jeep Cherokee xj . I turn the key to on and crank it but will not start . The only way I can get it to start is to turn the key to on and leave it there in that position until I hear a tic tick tick at the fuse box next to the battery then the fuel pump primes now I can start it this wait time is longer when it is colder out please any help would be greatly appreciated.

I’ve got a v8 WJ and it won’t even crank at times. I think it’s the SKIM and seems there’s no way to fix it here in Australia.

After replacing the fuel pump in my 2006 Jeep grand cherokee laredo 3.7 WK- Im now having a problem with a vapor lock and my new pump is making a ringing/humming noise off and on-is there a way to fix it with a inline check valve or inline filter of some sort. I have to release pressure on the fuel rail to re-crank it after it runs for more than 20 minutes/ which is a possible fire risk which makes it not safe to drive. Any suggestions? Reply

Great job. I have had my jeep down for 3 years!!😣 took it to 3 shops to no avail. I’m a great mechanic but not as great chasing ghosts and gremlins using high tech thingamajigs.. I’ve replaced two crankshaft sensors (myself of course) on my 1999 WJ inline-6 4X4. Bought it brand knew in 99’. First time I replaced it was probably 2007 with an aftermarket CPS. Then again in like in 2020, aftermarket.. And both times that they died, they died with me actually driving then coasting to a stop! Well I replaced that 2nd bad one with an aftermarket again.. Then only a week later that one went out!! Now no OBD2 comms & no 5v ref.. Sooo I replaced that week old one with another aftermarket!!! NOTHING! So I started replacing EVERY sensor, NOTHING! Ignition switch relay, NOTHING! Cleaning ALL grounds, NOTHING! Tried creating my own jumper 5V reference using a USB cable from watching another KZfaqr, Nothing! I’ve replaced the ECM using two different refurbished preprogrammed units using my vin, NOTHING!!! So I sent it to 3 shops and they couldn’t figure it out, NOTHING!!!! None of those shops were electrical shops because the electrical shops in my area were so far behind that I didn’t want my Jeep just sitting there for months risking liability damage to it.. So I towed it back home after it left the last shop. That was a year and a half ago. I just want my Jeep back running, damn! Makes me kinda hate Jeeps now. The dealer said it was too old so I had to use secondary shops because our two Jeep dealers wouldn’t look at it! Another reason to HATE Jeep… The only thing I can Ponder is that my CPS isn’t getting good ground perhaps. After changing that many of them I kinda stripped out the threads somewhat. So I added a little tape around the both to keep it tight. I mean it worked, I’ve done it before and it worked. It’s still tight. Also the CPS bolt receiver area is metal or copper and that tightens against the bell housing. I mean yeah, I wish it made more contact but I never had a problem the other times. No comms, cranks over but no start.. Where would you concentrate? Buying a 3rd new CPS this time Mopar?? Trying to run a self tapping bolt in my bell housing for the CPS? It’s already tight as hell just trying to get the original bolt back in, let alone trying to rig up another bolt or fastener! Hey I’ll pay you for some good advice, what do I have to lose at THIS POINT…😭 All I have is a semi basic OBD2 code reader, about a $150 type unit. And my simple multimeter. And yes I’ve tried unplugging all the things you did in this video and my comms or 5v ref. NEVER came back up. Those shops that looked at my truck NEVER found a bad wire, ground, NOTHING.. BUTTT, They took my word for it (because I bought two new ones) and they NEVER messed around with my CPS (as in removing it). And it only donned on my like a month ago that I had been using tape on the bolt to secure the stripped out CPS. The shops was saying they “think” it’s a bad ECM even though I proved them all with both of my refurbished ECM’s that had warranty on them both, from two different ECM providers.. I kinda don’t think it’s the ECM. But who TF knows….. ANY help would be a God Send!

I basically have the same problem, Crank, no start, no gauge's, no comm, but I do have a 5V reference and my skim light is on. I unplugged all of the sensors and still don't have any communication. What should I do next thank you

Awsome

Hi, i’ve same probel to my 1999 wj laredo 3.1 TD, and i don’t see this sensor to remplace

I'm not an electronics guy, i didnt understand ref voltage or how to use it. Might just get my jeep started now lol

Does this also work with the 4.7 V8

My 03 Grand Cherokee 4.0 is having the crank/no start issue with the Security Key light on. None of the gauges work either. I replaced the crankshaft position sensor, and it did not fix my issue. Suggestions on where to go next?

Hey I’m having fuel pump problems I just got a new pump and my pump is not turning on I have unplugged it and cleaned the plug and tested the relay and it’s still not wanting to prime can u help ?

ACCOMPLISHED Science of Diagnostics My teacher Thank you very much for sharing what you know WELCOME BACK 🙏 🤗 😀 ACCOMPLISHED Science of Diagnostics From Nick Ayivor from London England UK 🇬🇧

Does the fuel pump turns on?

Where are you located at

Hey brother, I need your help

I'm having this problem right now with my 2014 Jeep Grand Cherokee limited right now

The fuse is bad? Dont have time to wait on that show scanner