NEED HELP P0651

psa55

Original poster
Member
Oct 29, 2014
116
New Brunwick, Canada
Hey all,

I had a problem a couple of days ago with the TB... I had been out all day, home for a few minutes and went to run a couple errands with my daughter... went to start the TB and I got multiple dash lights, SES, and what I assume is the Transmission Service Light (Engine with arrow pointing down, directly above Oil Pressure Guage. It appeared to have at least one, if not multiple cylinder misfires, but it idled very rough, and ran.

I shut the truck off within 15 seconds or so and waited... I had been out all day with no issues. Gave it a try again... same issue, read the codes with Torque and got a P0651 and an issue with Secondary Air Injection system (P0411), which I have had for months. I accidentally, reset the codes attempting to save the log. While upset with myself, I shut the truck off, went and popped the hood...

Couple minutes later.... Fires right up... all is good... no lights, no rough idle, etc. Shut it off, try it again... still good. I look at my daughter and figure... all seems good at the moment... lets drive'r and see what happens.

Drove the vehicle all weekend, no issues. Spent some time reading and researching the P0651. Looks like I could be wire chasing for a problem with a 5V circuit, as this is an error on some platforms. I looked the main harness all over in the engine bay and can't find any wear spots or obvious problems. Other possibility I've read is bad senors. I have never replaced the Crankshaft or Camshaft sensors, and SAI system has been reading a bank is stuck open from time to time, which might be possibility. There are very little posts on here about this error code. Just wondering if anyone has some previous experience that might point me in the right direction. I'm not a big fan of driving too far, if this could be an issue that will rear its head again in the near future... or maybe its just a one off, oddity for a vehicle with 277k kms.

Any feedback would be appreciated.
Thanks,
Scott
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
That light with the arrow down is reduced engine power and serves to prevent a runaway engine situation. It is usually triggered by an issue with the drive by wire throttle system and is likely related to the P0651 code.

One possibility is the fan clutch. It can cause issues on the 5v reference circuit when it fails and is on the same 5v circuit as the throttle system. If you keep getting the code, try unplugging the clutch, reset the codes and see if it goes away. It can be run like this for a while if it's not too hot out and not running the A/C. Just keep an eye on the temp. If that's it, it will need to be replaced.
 

psa55

Original poster
Member
Oct 29, 2014
116
New Brunwick, Canada
Quick question regarding the fan clutch... I see the following AC Delco and a Four Seasons on RA. Both appear to be just the fan clutch, and do not include a new wiring harness. If required in the future, would you consider these two, or one of the more expensive ones that seem to include a new wiring harness. Just thinking about what could be the cause of the 5V reference circuit error..... if it might be the fan clutch or the clutch and the wiring.

https://www.rockauto.com/en/moreinfo.php?pk=1216717&cc=1441133&jsn=2241&jsn=2241

https://www.rockauto.com/en/moreinfo.php?pk=3909222&cc=1441133&jsn=2246

Thoughts? Just trying to be prepared should I need to purchase a new one.
Thanks!
 

Mike534x

Member
Apr 9, 2012
894
If it were me, I'd stick to either AC Delco, or the Hayden brand clutches. The other brands don't seem to be as reliable, or last as long as the OEM equivalent parts honestly. I know the wires going to the harness for the clutch have a tendency to braid up/become brittle with time. I'd pull and check the harness just to see if everything looks good.
 
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Mathoran

Member
May 3, 2012
54
Check which clutch is in your truck. The one without wires is a thermal clutch. If you have the electronic clutch in the truck now it will throw a code if you put in the thermal. Not sure why they list both types for your year.
 
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psa55

Original poster
Member
Oct 29, 2014
116
New Brunwick, Canada
Thanks fellas... it had me a little confused. While you guys were answering, I was under the hood taking a look. No wires... so thermal clutch. I'll stick with the AC Delco, if it needs to be replaced and I can pinpoint it as the issue. Doing my homework now, just in case.

Interesting to read that everywhere says to replace the water pump at the same time, but last year when I did the water pump, I didn't come across any messages to make sure I did the clutch, too. At least it's all been apart within the last 14-16 months.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Yeah. That's the thermal clutch for 08-09 only so that's what you have.

Our go-to is Hayden. ACDelco is good but usually overpriced. We don't have any data on the 4-seizin (that nickname is based on their compressors).

However, if your thermal fan clutch is working OK (it should as they are much more reliable than the electro-viscous clutches), don't bother as this has nothing to do with your 5v problems. Time to do more diagnostics.
 

psa55

Original poster
Member
Oct 29, 2014
116
New Brunwick, Canada
I'm now a little further ahead... 7 days today... no issue until an hour ago. Pulled out of work and it kicked into REP mode. Managed to make it home (about 7km) through a subdivision or two... but I made it home. Truck won't start at the moment, but I pulled a P0335 - Crankshaft Postion Sensor A Circuit. It is the only code. At least I can examine the wiring to the sensor and look to the replace the sensor, which i may just do anyways.

If I need the CKP, I believe I've read a Case Re-Learn procedure. Can I do that, or is that a dealership appointment? Approx. Cost/Time? I suppose when I have a little more time, I can look that up on here.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
A CASE relearn is usually required with a new crank sensor. Sometimes you can get away with it if there aren't any related codes after replacing it. If you do need it, it can be done either at the stealership or any shop that has a high end scanner like a Snap On Solus. Shouldn't take more than 10 minutes. It doesn't do anything for the function of the engine itself. It's just to report if the correlation between the crank and cam is out of spec, like if the timing chain is really stretched out.
 
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psa55

Original poster
Member
Oct 29, 2014
116
New Brunwick, Canada
Excellent... I believe I found the sensor (bottom of block, drivers side). All wiring appears to be in okay shape as far as I can tell with no new wear, but I'll have to investigate a little further. Hopefully I can get it in the garage on ramps, or jack stands if necessary. Looks like easiest way to change it out will be through the front drivers tire wheel well.

Glad to hear, that if the CKP sensor solves the problem, the engine will run fine. Will get a CASE relearn if necessary afterwards. Appreciate all this info.
 

psa55

Original poster
Member
Oct 29, 2014
116
New Brunwick, Canada
I'm waiting for a CKP sensor. All local shops were minimum 5 days... two dealerships minimum 3 weeks. Got the AC Delco coming for RA arriving Thursday. I am going to see if this solves my problems and get a relearn if necessary.

If all good after this, I am thinking about doing a couple other sensors to potentially avoid this in the future. Thinking about a CPS and a CPAS to start. What are your guys thoughts? Wasted money until it goes, or preventative maintenance? Would you consider these or any other sensors? For any your recommend, if you have a link to a how to, I'd appreciate it as well. (With regards to the CPAS, 5W30 only, every time the OLM pops a light, so regular and consistent oil changes)

Would love to have your opinions.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
CPS you could just pull out and clean it. It either works or it doesn't so no need to replace it. The CPAS would be worthwhile to check. If there's oil in the connector, it's done. If you pull it out and it's missing a screen, it's done. That one, for the trouble of pulling it out, I'd replace it unless it's fairly new. A cleaning is also possible.
How To: Clean The Camshaft Position Actuator Solenoid (CPAS) Picture Heavy
 
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psa55

Original poster
Member
Oct 29, 2014
116
New Brunwick, Canada
Good News! CKP Sensor arrived last Friday (took 7 days), installed it and have run it for a week. No codes, no issues, works great. Looks like I may be lucky and got away with out the CASE Relearn.

In the process, I discovered a I need a Diff Seal, as it is leaking around the CV Axle. Picked the seal up today and plan to get a litre of 75W90 in the AM (I have a litre on my bench).

Did a rear brake job today and came across a new issue. I have a part broken on the rear passenger side, but I'm not 100% sure what this part is? What is the horizontal bar, that is snapped in two? Looks like the Torsion bar is below it... what exactly am I looking to buy here?

20200626_181403.jpg

Lastly, @Mooseman, I'm gonna buy at new CPAS to change out with my next oil change. I've had no issues with it, and it is original to the TB and I'd rather prevent going another 7 days without my truck.

Appreciate all the info, as always!
 
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mrrsm

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Supporting Donor
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Oct 22, 2015
7,642
Tampa Bay Area
THIS is a VERY Interesting Video that comes from the "Scanner" Danner Boys that, In A NUTSHELL... proved out to be the CAUSE of this issue:

(1) The Code P0651 Sets and the PCM forces a Reduced Power Condition because the Five Volt Reference 2 Signal Wires service the Throttle Body (TPS) Sensor, The Crankshaft (CKP) Sensor AND the Accelerator Pedal (APP) Sensor... whenever the 5 Volt Ref. 2 Wire...SHORTS TO GROUND.

(2) By reading the On Line Mitchell Color-Coded Wiring Diagram... Paul "Scanner" Danner managed to isolate the Problem down to Purple & White Stripe 5 Volt Ref 2 Wire ...AND AFTER LOOKING OVER THE FAT WIRE BUNDLE THAT CROSSES THE TOP OF THE ENGINE...

(3) Danner finds a Spot in the Outer Under-Side of that Chubby Harness Covering where a STUD from the Engine side had managed to Poke itself through the Plastic Covering and gradually erode away the Insulation of the Purple & White Stripe Wire hidden inside...which...

(4) After reaching "COPPER" inside the Purple & White Striped Wire then Randomly SHORTED IT TO GROUND OUT THE FIVE VOLT REF 2 CIRCUIT ONTO THAT STEEL STUD.

(5) The OTHER Weird Artifact that was heppening here was that whenever these Reduced Power Events would occur, the Tachometer would become Disabled as well. This implies that for the sake of SAFETY, the PCM Shuts Down some other functionality to ensure that any Unsafe Conditions with an Out Of Control Motor cannot occur.

THIS is a Long Video...But there is MUCH to be learned here that might help anyone with a GMT360 vs. this GMT800 Truck to approach this problem like a Detective Danner did and sort out their unique Code P0651 Five Volt Reference Circuit "Short To Ground" Issues:

 
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