Found my "no bus" ,still crank and no start

[jeepdreamer]

The background: 2001 classic.
Following my 0331 head crack which resulted in a massively cracked block I did a motoclassic.After months of careful assembly, cleaning and painting i finally got it all together an installed. The big day finally came where I was going to fire it up. Put in oil and transmission fluid, easy peasy. Go to put in antifreeze and it comes pouring out. Seems the rear engine freeze plug want good. Just my luck I get to drop the tyranny again.
Next day I come back to the shop thinking today's the day. Once again go to add antifreeze only to disbelievingly see it coming out Again! This time from 2 (wtf!?!) on the block under the intake/exhaust. Pull those and have to order them because nobody had them in stock...3 day wait. In my frustration I decide to move onto something else, something supposedly easier, to feel better. Somehow what started as installing the t-case shiftier ended with me gutting the entire interior. . Found surface rust on the floors under a very nasty carpet so suddenly I was neck deep in repair work.
I mention all the above to give context of this ill project gone wild as well as my long suffered difficulties so far.
So a few days ago I once again return to the dream of hearing it fire up. Check it all over for the ten thousandth time, drop in a battery and hit the key.
Motor turns over , no odd sounds or spraying fluids, but it doesn't roar to life as hoped.,ok... Check the dash and see the dreaded noBus on the odometer. I've never experienced this so spent a goodly while searching online for explanations.
4 days of googling, trial and error, and lots of gnashing of teeth with no joyful first start. Tested the crank sensor and all its wiring. No resistance. Thoroughly inspect, reclean, and secure all the grounds. Even go to the extent of making new +&- cables from some 0 ga wire.
Also added extra grounds to tie the dipstick tube bolt, the 2 front block bolts,etc so I'm confident in good on grounds.
Long story short... I discovered that my no bus came from the airbag module which normally mounts under the center console. Remember where I said I gutted the interior? Yup... Seems that that module grounds to the tyranny hump.i had it out in prep for bedliner...found it by pure accident!
So with it in i crank the key and SURPRISE! No bus is gone! Cool, right?
Well...no.
While its still offering no noBus it also still won't fire.
In honestly about at my wits end. Hooked up the snap on scan tool but it went/cant communicate with the jeep.
So I would greatly appreciate any thoughts or ideas you guys could offer me.
Help!

 

[jeepdreamer]

I guess what I'm asking is this. Since the no bus has left but it still won't talk to the scan tool, what do i look at now?
Could any of the other wiring things inside effect this? Things like seatbelts or parking brake, interior lights, etc?? Maybe not enough to kick the bus but still confusing the computer??

 

[Digger87xj]

Grounds at the dipstick attached?

 

[Tim_MN]

.... Hooked up the snap on scan tool but it went/cant communicate with the jeep. ..... its still offering no noBus it also still won't fire.

With a no-start, and no communication to a scanner, I would suspect Crankshaft Position Sensor issues. Genuine Jeep CPS ? Is the Cam Pickup Sensor assembly properly indexed when at TDC ?

Inspected all of the wire plugs for damage/corrosion/clean and tight connections ? Inspected all the wire harnesses for damaged wires or failed wire splices from all the recent work and manipulation of the wires ?

 

[jeepdreamer]

Grounds at the dipstick attached?

Yup. Cleaned and installed. Even built an extra wire to go from it to the two at the front of the block as extra ground.

 

[jeepdreamer]

With a no-start, and no communication to a scanner, I would suspect Crankshaft Position Sensor issues. Genuine Jeep CPS ? Is the Cam Pickup Sensor assembly properly indexed when at TDC ?

Inspected all of the wire plugs for damage/corrosion/clean and tight connections ? Inspected all the wire harnesses for damaged wires or failed wire splices from all the recent work and manipulation of the wires ?

Been through all the wiring. Set TDC and aligned the timing marks. Adjusted the oil pump to 11 o'clock. Used a spray lube straw to align the holes in the drive with the pick up.

I'm at a loss... at the point I guess I'll go buy a new crank sensor and cam sensor. Hate to since it (crank sensor ) doesn't read any resistance but I'm just stumped.
Since bolting the air bag module back in seems to have fixed the no bus issue... is there any chance the trans shifter being out is a culprit? I know they often cause no crank (mine never had that issue, yet) but idk if it would cause a no start?
Also, could a dead battery in the key fob have any effect? I'm grasping at straws I know but I'm just stumped. And broke.

 

[Tim_MN]

The CPS should show open, or no resistance. Genuine Jeep CPS ? Cheap Chinese CPS are well known to be weak, out of specification, or even failed right out of the box.

A faulty NSS, mis-adjusted NSS, or "the trans shifter being out" would cause the starter to not engage at all.

The key-fob has no effect on anything.

If the battery has been disconnected for an extended period of time, the PCM may have lost its idle settings and you will have to feather the gas pedal to start and idle until the PCM re-learns.

 

[jeepdreamer]

Thanks Tim...
The original cps was jeep and was the one I drove the jeep into the shop with. It tests good @ no resistance.
I have a second original jeep one that was on my working 2wd aw4 (same year etc) and it tested good also.
Went and picked up a crap one (98 bucks! Wtf?) From vatozone and it didn't change anything.
I know it's getting fuel because I've cranked it enough you can smell it. I've played with every wire I can find, checked fuses and relays. Reset TDC / timing 3 times now just because I'm at a loss.
I'm honestly about to throw gas and a match on it. I wish I knew a really skilled auto electrician that does house calls (well, army base calls).

 

[Tim_MN]

Feathered the gas pedal ? Really, if the PCM has lost memory, it will not start normally.

With a no-start, and no communication to a scanner, I would suspect Crankshaft Position Sensor issues.

Inspected all of the wire plugs for damage/corrosion/clean and tight connections ? Inspected all the wire harnesses for damaged wires or failed wire splices from all the recent work and manipulation of the wires ?

A simple physical inspection for damaged wires, chafed wire insulation, and failed wire splices, along with continuity testing should be performed, starting with the CPS wire harness.

 

[jeepdreamer]

Feathered the gas pedal ? Really, if the PCM has lost memory, it will not start normally.






A simple physical inspection for damaged wires, chafed wire insulation, and failed wire splices, along with continuity testing should be performed, starting with the CPS wire harness.

Disconnected the harness at the firewall leading to the pcm. Shows 0 resistance. Not sure where it goes above that plug, across the motor towards the drivers side..
The pedal isn't bolted in (like the airbag module wasn't )...I'll check that now....

 

[jeepdreamer]

Bolted the gas pedal back in and pumped it before, during and after spinning the motor. No change.

 

[jeepdreamer]

Checked fuel rail... right at 42-43psi.

 

[Digger87xj]

spark and injector pulse during cranking?

I thought there is supposed to be 2 factory ground loops at the dipstick stud?

Also, not to discount your work but the ground cable from stud to stud on the engine block is pointless. better off attaching dipstick stud<>firewall.

 

[jeepdreamer]

I'm honestly stumped at how to check the coil pack for spark. My belief is its not being told to fire at all... any thoughts? I don't see how the old method with an actual distributor could be done?
And no worries for pointing out my odd attempt at adding grounds. Though it seems logical in my mind I see your point.
There is one small wire coming from the harness that attaches to the stud by the firewall,pass side.
Since its often a trouble maker I figured why not add an extra tying it to the front studs? Maybe to the "frame" would have been better...if still a waste?
That new extra wire I ran goes to the pair of front studs where two more wires from the harness join it. Also the main ground wire from the battery goes to the rear of that pair of studs. There is an extra wire that goes from the front stud to the vertices bolt on the motor mount to the frame.
And as far as I know there has only ever been one wire on that rear dipstick stud?? Am I missing something? ?

 

[Digger87xj]

remove the coilpack leaving it plugged in and use 6 spark plugs. they do all need to touch a ground; you can use something like mechanics wire and run it along all the plugs making a loop around each of the threads and ground the wire. you'll need a helper to crank while you watch for spark.

The engine to engine ground loop is pointless because the engine block is one big ground. An extra engine to body ground is never a bad thing though. leave it attached to the dipstick stud and run it to the body somewhere.

 

[jeepdreamer]

So if it's not creating spark, as I suspect, is it a bad coil pack assembly or simply not getting told to do so? I'm not sure how to test the plug for the rail to tell...?

 

[Digger87xj]

again, I'm almost positive there should be another ground loop attached at the dipsick stud. 2 loops, 3 or 4 wires total.

 

[jeepdreamer]

Quick Google only shows the one wire to the dipstick tube stud.

^broken one via google^

There's another stud a bit forward of it that has some weird thingy on it that has to do with...?

(God, wash that thing! )

 

[Tim_MN]

Does the OBD trouble code scanner connect ? Tried a different one ?

If both of the OBD trouble code scanners cannot connect, there would be little doubt you are still dealing with CPS issues, which in most cases means no-spark.

 

[jeepdreamer]

Had a buddy play with the scan tool last night. It connects but doesn't really communicate. He tried something called "global"?? And wasn't able to even pull that info.
So here's a randumb couple questions.
There are 4 wires coming from the brain thing on the drivers front fender by the airbox. Those 4 wires ground on two screws (now bolts) just through the inner fender. Is that it? Does the brain thing ground to the fender also with its 3 screws that hold it on?
Also, what's this thing on the stud in front of the dipstick stud?