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Discussion Starter #1
I've scoured the interwebs and found the issue is most likely the exhaust cam sensor on bank 1. I've already got the new sensor in-hand and ready to install. My issue is, I've tried to pull the current sensor out but didn't want to break the plastic as it's the factory sensor. Is there a "nice" way to pull that sensor? It's definitely a booger to get to, I had to un-mount the fuse box and shift it around to get my wrench down to the bolt. I had some rotation on it, but I'm pretty sure it just comes straight out, correct?

Any help would be appreciated!
 

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Most likely comes straight out but has some sort of clip securing it in place. Should be visible on the replacement sensor.
 

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Discussion Starter #5
Well, I replaced both sensors on that bank and still have the code. I took it to have the annual safety inspection done and the mechanic pulled a code for high flow on the evap purge. I’ve got the part coming so I’ll let you know. I’m having a hard time starting the car right now, so I hope this takes care of it.
 

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Discussion Starter #6
Okay, update!!!

I replaced the EVAP purge on the engine and still have the issue. I keep pulling the codes as the same P0340. I'm curious to see if it's a wire that has worn or possibly the ECM.


Does anyone have an idea of where the wires rub against the engine and potentially cause a short? I've read it's a semi-common problem with the older Acadia platform. Any help would be appreciated!! Thanks!
 

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Does anyone have an idea of where the wires rub against the engine and potentially cause a short?
I don't believe anyone can define one 'common' place where rubbing occurs. You'll have to do your own thorough inspection of the wiring harness. The code suggests tracing harness segments which contain camshaft position sensor wiring.
 

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Discussion Starter #8
Okay....


I'm asking if anyone has seen this or experienced this on their vehicle to narrow down my search area.
 

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Good luck with that. I haven't seen any 'in depth' discussion about it in my time on the forum.
 

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acadiarob1776,

I don't have an Acadia, but I have a 2011 Equinox V6 (bought new), and I have the Factory Service Manual for it. For a code P0340 on my Equinox, it says to check the routing of the wiring for:

1.) Aftermarket electrical equipment (anything like that on your Acadia)?

2.) Close proximity to solenoids, motors, and relays (that could cause Electrical Interference)

It also talks about checking "Counters" for all four Camshaft Position Sensors ... but you probably cannot read these with a basic Scan Tool. Probably need access to Dealership Scan Tool (or maybe an Independent mechanic has a scanner that can reveal these Counters). All four should be incrementing while the engine is running.

You can also test the three terminals on the Camshaft Position Sensor Connector:

Terminal #1 (left) is the "Low Reference Circuit". Should have less than 3 Ohms between this terminal and ground.

Terminal #3 (right) is the "ECM-supplied 5V Reference Circuit". Should have 4.5 - 5.2V between Terminal #3 and ground.

Terminal #2 (center) is the "Output Signal Circuit" is where the Sensor produces the digital output pulse which produces an "image" of the camshaft Reluctor Wheel back to the ECM. The Reluctor Wheel has four teeth, all different widths. I believe this part sits on the front of the Camshaft Position Actuator. The sensor produces 4 varying width output pulses per camshaft revolution. You can pass a steel object by the tip of the sensor repeatedly to test it while observing the Counter parameter is incrementing (again - IF you have the Scan Tool).

For code P0340, you can have:

1.) an Open/High Resistance or a Short To Voltage on the "Low Reference Circuit".
OR..
2.) an Open/High Resistance on the "5V Reference Circuit"
OR...
3.) an Open/High Resistance, a Short To Ground, or a Short to Voltage on the "Output Signal Circuit" (from the sensor)

BUT ... this is for a 2011 Equinox. Not sure if the Camshaft Position Sensor connector (called a B23A, B, C, and D on the Equinox) is the same on the Acadia.

Also wonder if the existing wiring could be temporarily bypassed with directly-connected wiring to prove the existing wiring is the problem? You'd need wiring diagrams for that. Maybe you could sign up for AllData subscription online? They were offering $13 annual subscriptions at Christmas on SlickDeals.com
 

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...
Also wonder if the existing wiring could be temporarily bypassed with directly-connected wiring to prove the existing wiring is the problem? ...
That's not a very wise recommendation considering sensors are used for digital data transmission. One misstep could result in other system faults. The same applies to solenoids and other control devices which not only transmit, but also receive digital data.
 

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That's not a very wise recommendation considering sensors are used for digital data transmission. One misstep could result in other system faults. The same applies to solenoids and other control devices which not only transmit, but also receive digital data.
I think it’s just a return of the reference voltage (or 0V) 4 times per camshaft revolution at variable length depending on engine speed. You probably could could have a test connector directly wired.

But I’m also wondering if the sensor is working “fine”, but just not completing the 4 pulses within the timeframe the ECM expects - which might indicate an early sign of a timing problem? Just guessing, though. Would probably need an oscilloscope to see all the waveforms.

Also - what about the possibility of a damaged Reluctor Wheel, or a need to replace the entire Camshaft Actuator (with Reluctor Wheel)? You’d have to open it up to see.
 

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Discussion Starter #13
No, no aftermarket electronics. Everything is as is from the factory. The replacement sensors were AC Delco and I was getting 5VDC on the line and like .5 ohms with the original sensors but I replaced them anyways.

My mechanic has a nice scan tool but I'm struggling to find a time to drop off the Acadia as it's our family and only car at the moment. Hence my questions about the wiring to attempt to pinpoint further before going to the shop.

The longer starting is not a problem for me, just a semi-major annoyance. I charge the battery once a week overnight to compensate for the longer cranking times. I've had the battery tested and it is operating at 98% capacity.
 

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Discussion Starter #14
I'm at 123k miles and still have the original transmission, so if it is the timing chain.... I'm buying another car. I wouldn't drop the engine and not replace the transmission at the same time.
 

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No, no aftermarket electronics. Everything is as is from the factory. The replacement sensors were AC Delco and I was getting 5VDC on the line and like .5 ohms with the original sensors but I replaced them anyways.
Yeah, but maybe that 5V Reference Voltage is spuriously dropping out (or down) while the engine is running? You'd have to have a way to show the waveforms and their history in a trend.

Maybe another code is coming to bring the problem into better focus?
 

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Discussion Starter #16
Well, have an appointment set for the 14th to get the diagnostic work done. My mechanic had another Acadia in the shop with the same code with the same ballpark miles but newer year and he found it was the VVT solenoids not working right. I'll update once the service has happened.

Edited for spelling.
 

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Discussion Starter #17
Well.....

My mechanic wants to start with changing the spark plugs and go from there. The Acadia is at 123k+ on the clock with the factory plugs still in. Does anyone have any other ideas?
 
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