2007 Jeep Grand Cherokee Stalling

Daryll Diagnostician Seymour, Tennessee Posted   Latest   Edited  
Discussion
Snapon Zeus
Driveability
Electrical
P0300 — Random/Multiple Cylinder Misfire Detected
P0688 — ECM/PCM Power Relay Sense Circuit/Open
P0201 — Cylinder 1 Injector "A" Circuit
P0204 — Cylinder 4 Injector "A" Circuit
P0633 — Immobilizer Key Not Programmed - ECM/PCM
Stalling

Greetings everyone, 

The purpose of this post is to generate discussion on diagnostic strategies. This is an actual case that I recently collected data on. 

Ready to do some discussion?

A friend asked for help on a vehicle that would stall pretty frequently. 2007 Jeep Grand Cherokee 4.7 V8. PCM was replaced and programmed last year for a misfire problem. Misfire concern was cured. P0633 set due to using an aftermarket pass-thru, constantly occurring code but does not impact vehicle operation.

Come summertime here, vehicle began having frequent stalling events, worst during the hottest part of the day. A code scan at that time revealed a P0688 ASD/Main Sense Circuit. After some driving post-code clear, setting codes P0300 mutiple cylinder misfire, P0201, P0204 injector circuit faults.

Before I indulge any further in the storyline, I'm interested to hear where you would take this situation? What would you do next and why? What equipment would you use? And what would you be looking for?

The first image is voltage measured at 4 separate points in the same circuit. 2nd image, yellow and blue are power side, green and red are ground side. I'll explain more as the discussion grows, I have more images to share, and willing to post the capture files if anyone desires. Let's hear some thinking! Go....

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Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
 

It’s late, so thinking is next to impossible! What I‘d be looking for? Wiring diagram that shows power feeds to injectors and the Power relay. Then hoping there are good places to stick an amp clamp to see on which branch an intermittent short to ground happens...

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

In the first image, each color here corresponds with the channel color. Blue is injector power, red is coil power diag​.​net/file/f4l3qx5dk…

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Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
 

Thanks, Daryll, the wiring diagram shows everything perfectly. I do have a question about the second capture: the red (#4) trace is the relay control. ON = around 0V, OFF = battery voltage. Why would you then use 0.2V/div scale for it, like you are scoping a full-time ground? The fact that the Zeus does not report "channel over-range" is disturbing, but not surprising. SnapOn does not think it…

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

I recorded in that scale to match the green trace scale, since green is ground and the relay control is being pulled to ground, wanted to see the differences between the 2

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Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
 

Ah ok, I see why you did it that way. Please correct me if I'm wrong, but is it the only way to get a (vertically) zoomed-in view in a 4-window layout? If so, would the 1- or 2-window layouts be more appropriate for such signals so that we can clearly see the lower and the upper portions of the signal? Just trying to figure out advantages and drawbacks of each layout as the user guide does not…

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Ray Diagnostician
North York, Ontario
Ray Default
 

Looks like the stalling is caused by a P0688 ASD/Main Sense circuit. I would scope the 4 wires to the ASD relay to see which circuit is dropping out. The ASD relay is in the TIPM. With the engine running, if you lift the TIPM from it's bracket, does the engine stall. In your first and second images, which circuits are you scoping? In the second image, the red ground is at .8 to 1v. Which…

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

In the first image, yellow is ASD relay output at relay, green is ASD sense circuit at PCM, blue is injector B+, red is ignition coil B+. You can see the same waveform at 4 points. In the second image, I moved green to the PCM ground, red was moved to ASD control at relay

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

So at that point you know the ASD Relay output is dropping, because the command from the PCM is dropping. Next I'd want to see whether the PCM is losing any inputs. Most valuable players there would be CMP, CKP, and any switched powers, either straight from the WIN, or whatever they use here as a PMM (GM term, I know, but I really like it). Interesting that your PCM ground is steady. Since you…

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

Geoff that’s an excellent thought process. I agree that would be a great route to go. In this particular case, all inputs remained normal

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Not exactly sure what you want so ill give it a shot lol. Im going to act like I didnt see these captures for my first response. The ASD relay powers the coils and injectors and sends some IGN inputs to the PCM. Very similar to a Powertrain or Engine Controls Relay on a GM vehicle. I guess if I was using a 4 channel I would hook 2 channels to the ASD relay control wire at the PCM and at the…

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

In the 2nd image posted, I had moved the green channel lead to the PCM ground, and the red was moved to the ASD relay control circuit at the PCM. The process you described pretty solid, seems that you laid out intentional direction and expected results. I also see that you had an understanding of how the circuit operates, which is where I see many techs today struggle. The purpose of even…

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Thanks Daryll. Without making a rant or being a jerk I will try to say something in regards to your comment on techs struggling with circuit design or function. I work in a large very busy GM Dealer. The amount of parts shotgunning is incredible. And in saying that I would consider us one of the better dealers in the area. In 2013 the dealer invited John Thorton down to give us a class. He of…

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Samuel Technician
Somers Point, New Jersey
Samuel Default
 

ABSOLUTELY AGREE WITH YOU CALEB!!! I could ramble. To keep it simple I despise techs who do not complete the diagnostic process and simply shotgun parts. What really sends me over the top is when they guess and they are correct!!!! WTF...as an industry we are supposed to be leaning away from shotgunning. The flat rate system breeds bad techs. Even the good techs in a flat rate system know the…

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

Caleb, this is wayyyyyy off topic, but it's better to buy business tools and equipment on credit/loans. The payments AND interest are all written-off as top line expenses. The most successful shop owner I know built his whole business that way. The guys who sink their own money in are all broke. YOUR money should be for your home and food. If you already own a scope, then make sure to "buy it"…

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Thanks for your concern Geoff. I fail to see how getting a loan for anything ever is a good idea. A credit card to build some credit is one thing. Also I know I know multiple individuals( including my father, who has had his own business for 30 years) who started there business only with cash and never borrowed a penny and are very successful today. I do agree with your comment of paying myself…

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Samuel Technician
Somers Point, New Jersey
Samuel Default
 

This is debatable....I watched Mark Cuban say that if you need money to start up a business, you shouldn't be starting one. Start with next to nothing and build was his theory....when I opened brick and mortar, I invested in small items....trans flush machine, etc. I didn't fully listen to that, however, I did see his point. The business is not guaranteed and if it fails, you are still on the…

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Sean Owner/Technician
Santa Ana, California
Sean Default
 

I was following this thread and it seems like it just stopped after the conversation about finance, I learnt a lot form this but was curious as to the cause of the stalling and code...have followed the same vehicle for a while but it is intermittent, have to drive it for more that 49 miles when it does stall, has random misfire code, misfire for cylinder #8, my ground at ASD did go to 0.1 volts…

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

For those following, I have been lacking in my keeping up with this, so here's an update. Many of you have commented with some great strategies that could be applied, and that was the whole purpose of doing this to begin with. It wasn't an attempt to diag the car, but merely an opportunity to explain how you personally would go about diagnosing this type of problem. So here's part 2 of this. In…

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Sean Owner/Technician
Santa Ana, California
Sean Default
 

I wonder if it will make a difference if you probe it at the computer instead of at the ASD relay terminals? or is that where you have the red trace-at terminal 3 of the ECM?

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

Red trace was measure at the ecm pin for ASD control

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Sean Owner/Technician
Santa Ana, California
Sean Default
 

Sorry but I can not think of nothing else other than maybe the computer is not pulling it to ground either because of internal corrosion, curious why the yellow line mimics the blue line? why is it smooth until you release the ground???

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

Yellow is the ASD relay output at the relay, blue is the ASD sense terminal at the pcm. As long as the circuit is intact, should have the same waveform at both points

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