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no bus, no gauges, no crank.

The1AndOnlyBug

NAXJA Forum User
Location
Denver, Co
So I know that there is a dozen posts that are similar, but hear me out.
So I've had a dozen codes ever since I replaced the engine, but since I still was getting 14-15 mpg I wasn't too worried. Well I stopped at the carhart store the jeep was running normal came back out and the jeep wouldn't start, turn the ignition, and the gauges don't test, jeep will not crank over, and after 30 seconds to a minute no bus is displayed. I tried unplugging every sensor one at a time cps, tps, cam sensor, temp, ect. And nothing made any difference. I borrowed a multi metre from a co-worker and was trying to test the pcm, but I don't have a fsm to figure out what should read what.
My culprit is the pcm but just having started a new job on Monday money is tight for this week, so i can't just throw parts at it hoping it will fix itself. If it helps pin 22 on the black connector had 12v pin 2 had none pin 1 had none, the grounding pins had good continuity and I can't remember if pin 17 had 5v I believe it did but I don't remember.

I've got a picture of that list of codes if you guys want to take a look
 
Define and fully explain "jeep will not crank over" ? Does the starter engage the flywheel and move the engine, or not ?

Have you tested the most common and most likely suspect for engine cranks but won't start with gauge cluster/no-bus symptoms, the Crankshaft Position Sensor ?

If the OBD-II system is providing Check Engine Light Trouble Codes, you should be diagnosing and problem solving for the trouble codes.

Down load the Trouble Codes and post the exact four digit P_ _ _ _ code numbers.
 
https://photos.app.goo.gl/xy7soPeAeWFBeDWh1
In case you can't see the photo this is what I had for codes after towing a uhaul trailer from VA to ME maybe this will give a clue to to my current problem.
P0174 Fuel system lean (bank 2)
P0123 TP sensor circuit high input
P0118 ECT Sensor High input
P0108 MAP sensor high input
P0113 IAT sensor high input
P0204 injector circut/open cylinder 4
P0300 multiple cylinder misfire detected
P0301 cylinder 1-10 misfire detected
P0302 cylinder 1-10 misfire detected
P0303 cylinder 1-10 misfire detected
P0455 EVAP Large leak (0.80") detected (There when we bought the jeep)
P0151 O2 (B2 S1) Circut Short to ground
P0122 TP Sensor Circut Low input
P1694 No PCM Bus messages
I had the majority of these codes once I got up to PA from VA I then replaced the number 2 injector (it was leaking) the TP sensor and the front lower 02 sensor, reset the codes and this is what came back.

I didn't test the cps because it didn't make any difference when I unplugged the cps and turned on the ignition.
As for not crank the starter doesn't turn over, fuel pump doesn't kick on. I checked all fuses swapped out relays with no change.
Before anyone asks the battery is fine, first thing I checked.
 
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If you do not have a Check Engine Light trouble code reader, buy one. A basic code reader will work, but upgrading to one with live data display is a good idea.

Solve the trouble codes in numerical order, lowest numbered codes first. Often higher numbered trouble codes are caused by faulty data or by the failed sensor that is causing the lower numbered codes.

Note that many of the codes are High Voltage. A recent engine swap and voltage related trouble codes points us toward wire harness issues, likely a short circuit to 12 volts positive. Moving the wire harnesses all about and/or accidentally crushing a wire harness can lead to failed wire splices and/or cut wires. Many of the OBD sensors are spliced inside the throttle body wire harness. Improperly secured wire harnesses can lead to melted insulation from hot exhaust or chafed wire insulation from sharp sheet metal edges.

I always start with a wiggle and poke check. Poke around all the wire harnesses and visually inspect from one end to the other. Wiggle them all. Unplug each wire harness and test continuity. Test each OBD sensor for 5 volts input and continuity to ground. While unplugged check each wire plug for wire plug pin damage, bent/crushed pins, pushed back pins, and corrosion.


The P0151 and the P1694 catch my attention, I would start troubleshooting at the O2 sensor and transmission wire harnesses. Unplug the Transmission Control Module (TCM) and see if any codes clear.

P1694 will set if no CCd bus messages are received from PCM for 20 seconds or invalid messages are received for 20 seconds.

Possible Causes
- Faulty Crankshaft Position Sensor.
- Faulty TCM.
- CCD Bus (-) circuit open between PCM and TCM.
- CCD Bus (+) circuit open between PCM and TCM.
- Transmission CCD bus wiring damaged - CCD Bus (-) circuit open between PCM and TCM.
 
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Moving the wire harnesses all about and/or accidentally crushing a wire harness can lead to failed wire splices and/or cut wires

This was one of my concerns, the guy who's shop I used for the swap just sells used jeep parts, he helped me remove the engine (this was my first time, and I figured he had the experience to know what he was doing) well in removing it he forgot the 2 bolts from the block to the flexplate (I think) and was slamming a 4 foot pry bar against the wiring harness trying to disconnect the engine/transmission.

You think fixing any of these codes will fix the no bus? I figured since the jeep ran fine then it wasn't a big deal.
 
If there is a no-bus and the Cherokee runs, usually the cure is to clean the connector plugs on the rear of the instrument cluster.
 
Well I've had these codes for a while. In my first post I explained that the jeep is no longer running, it will not crank over (no power to the fuel pump or to the starter) the gauges do not work, and is displaying no bus. I have a multimetre and a tone tracer. Since I don't have money to throw parts at it, besides testing the cps (which I don't think is the problem) I am lookung for what pin should read what on the pcm so I can test the pcm .
 
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Diagnose and problem solve for the existing trouble codes. It is very unlikely that the PCM has any issues, and even if it does and you install another PCM, you still need to solve the existing trouble codes. Since you witnessed the guy pinch the wire harness that is an obvious starting point.
 
Diagnose and problem solve for the existing trouble codes. It is very unlikely that the PCM has any issues, and even if it does and you install another PCM, you still need to solve the existing trouble codes. Since you witnessed the guy pinch the wire harness that is an obvious starting point.

Yes and no. You need to start with the circuit faults. Do you have 5v ref to the sensors? Signal wires to the pcm ok? They shouldn't have voltage on them with the sensor unplugged. Sensor grounds ok? If you don't have a 5v ref, cut the ref wire close to the pcm and recheck. If the 5v comes back, there's a harness problem. If not, you have a pcm or power/ground issue.
 
You may want to check your ASD relay (and the engine related relays) under the hood. I had a similar situation which was caused by a bad ASD relay. It had fallen apart internally.
 
Well, so far what I've discovered is nearly nothing, I've tested the cps no resistance across b and c. I've dug into the wiring harness and found absolutely 0 crushed or cut wires.
Today the fuel pump works fine.
Several times the gauges have worked normally and no bus didn't display, but still wouldn't crank over.
I have tried to recreate the above mentioned symptoms with no consistant results.
I have unplugged every sensor one at a time hoping that I could figure it out that way, no luck.
I tried to diagnose p1694 with no luck.
I'm gonna hit it again in the morning and see what I can figure out so if anyone has any other f'ing idea's let me know....

You may want to check your ASD relay (and the engine related relays) under the hood. I had a similar situation which was caused by a bad ASD relay. It had fallen apart internally.
Already swapped relays with no change.
 
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You may want to check your ASD relay (and the engine related relays) under the hood. I had a similar situation which was caused by a bad ASD relay. It had fallen apart internally.


That's my initial thought too as it can cause all sorts of bad signal codes. As can bad or missing grounds.
 
So everything has been intermittent no matter what I have done, I.E. sometimes all the gauges work, sometimes only the gas gauge works. But one new symptom is the front 02 sensor relay has started rapid fire clicking even after swapping relays...

QUOTE=lawsoncl;246526911] As can bad or missing grounds.[/QUOTE]
I double checked all grounds, removed, cleaned, and reconnected.
 
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Well so since it's my only vehicle and i don't have the proper knowledge or equipment to diagnose the jeep I am bringing it to a garage for them to diagnose it... But something new I discovered.... at low voltage the jeep acts like it normally would with a low battery... the starter just clicks... as soon as I hook jumper cables to it it goes back to not cranking and no bus shows up..... wtf....
 
So... the guy at the garage tells me that he hooked a jump pack to it and the jeep started right up...... he said my battery is junk and once I get a new battery then he can test further.... what doesn't make sense to me is when I jumped it last night it made it do a no bus again....
 
We'll the jeep is back on the road, believe it or not it needed a starter.... the solenoid crapped out and must have been shorting out the pcm... He replaced the starter and everything else went away... I no longer have a "no bus" the cel just came back on after 25 miles, I'll find out what that is tomorrow.

Sent from my SM-G950U using Tapatalk
 
Ok, so the jeep runs a little rough, I'm gonna start with the O2 sensor. The running lean should be fixed once I replace the intake (P.O. over tightened the bolts and cracked it) any other places I should start?
I also tested the TPS and at w.o.t. it wouldn't go over 3.25V I tested the old TPS which tested fine so I reinstalled the old one.
5725ea43f9b3f4051208c00435f6d7cc.jpg
 
We'll the p1196 and my check engine light went away on there own, it was replaced with a misfire cylinder 1-10... I notices the crack on the intake is a little bigger so my #1 priority at this point is to replace the intake from the JY
 
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