Check Engine Light

[Mike McGill]

Hello all I have a 2005 Beaver Monterey with a Cat C9. About a year ago both the Yellow and Red check engine lights came on. It felt like I had lost all power when I pressed the gas pedal and nothing happened. However when I backed off the pedal for a few seconds everything went back to normal and the coach ran fine. This is a continuing problem and has has happened several times since then, the check engine lights come on, power goes down, I back off and it runs fine The coach has never shut down.

Below is the list of things I have done to try and find the problem.

1. Replaced the throttle control speed sensor.
2. Have had diagnostics ran by a former Cat mechanic using the good Cat software program who suggested I replace the atmosphere control sensor which I did.

Note: Each time this problem has happened I have checked all gauges Water temp fine. Oil fine transmission fine. I recently posted on the form asking about using the dash gauges and was told to switch over to the Aladdin data because it is more precise.

4. When the check engine light came on this week the Oil pressure on the Aladdin was at 0 and ran back up to 85 to 90 Lbs a few times then it ran fine.  But the oil pressure gauge on the dash hardly moved at all and stayed steady at 70 to 75 lbs.

I stopped and had the oil changed and a piece of gasket about an inch in size came out of the oil pan. No idea how it made it in the pan since the engine has only has 55,000 miles and has not been rebuilt. So now we think we have solved the problem by removing the debris in the oil. ( Wrong )

5. I drove the coach to Indio and the lights came on again so to play it safe I had the oil pan dropped and cleaned so we could make sure there wasn't any debris in the oil pan. It was all ok and the oil was clean.

6. The mechanic told me that I should try disabling the Aladdin system because it might be creating false signals to the engine and that was bad for the Cat computer.

Left Indio to drive to Santa Barbara and unplugged the engine data connect on the Aladdin so now no power to the Aladdin and the check engine lights came on again but the dash oil gauge stayed strong.

My next idea is to replace the two oil sensors on the engine and i'm hoping it could be one or both of these I think one must be for the Aladdin and the other for the dash???

Sorry for being so long winded but think anyone reading this needed the whole story.

Any thoughts?

thank you
Mike McGill
2005 Beaver Monterey
Cat C9

[Eric Maclean]

Mike
Do a search on here for a post by Russ Mann (2006 CAT C9 400HP oil pressure) in 2019

on his C9 oil pressure issues it would appear yours are the same symptoms
The early C9 s used a piston type oil pump that can be problematic which Cat replaced later with a gear type pump but the oil pressure fluctuating that your are seeing is more likely an oil pressure relief valve sticking . As the post Russ posted explains you should be getting a code for( low oil pressure ) to accompany the check engine and red light .
Give Dave Atherton a call and your engine serial number he should be able to walk you through this.
By the way don't drive the coach with the red light on the Fred light is to tell you to shut down before damage is done.

Hope this helps
Eric

[Mike McGill]

Thank you Eric I have talked with Dave when we ran his report the low oil pressure did not show up on his read out. I will call him on the oil pump. Thanks again

[Eric Maclean]

Mike
I would start with an oil pressure sensor as the aladin is reading straight off the engine ECM which means if the aladin is seeing the oil pressure drop to zero so is the engine ECM and the ECM is programed to go into engine protection mode to save the engine from damage.when in engine protection mode the ECM will derate the engine limiting torque output and eventually shutting down the engine . Your problem is intermittent and apparently doesn't last long enough to cause engine shut down
At this point your looking at either the sensor is faulty giving faulty low pressure reading or there is actually an oil pressure problem like sticking oil pressure relief valve.
My money would be on the oil pressure sensor.
The real question is where did that price of gasket come from that you found in the oil and is it possible that there is something sticking the oil pressure relief valve.
I'd start with the engine oil pressure sensor as that is the easiest and cheapest fix.

https://www.google.com/search?sxsrf=ALeKk0206cLe9sEhTZDXfPbbROnLt9rhLg:1617985825430&source=univ&tbm=isch&q=cat+c9+oil+pressure+sensor+location&client=tablet-android-lenovo-rev2&fir=QJWv1MP51rn7AM%252COwTM334PX9DXBM%252C_%253BSkID5EXPXcRQrM%252CM_QlHdwaAD7LzM%252C_%253BuoYRvUXMaOqHHM%252COwTM334PX9DXBM%252C_%253BF141ZZFP0ctjvM%252C2BBQaeqnetEZDM%252C_%253Bff4gH54ow9QBHM%252CBAIsgu-2cvC0xM%252C_%253BQ_cgBeZcGl2e8M%252C3nCF4wKB6FSwRM%252C_%253BbQ69baBZwsaz_M%252Coer3qaatN9rGNM%252C_%253BgkWfPikuE-EmtM%252CTmu7Cmy9gBwYwM%252C_%253B0j9qdZNEwaTrqM%252Coe1TckRbTnH5tM%252C_%253BZZ6P7We2l7kbfM%252Cd6cSP2hl_TnxxM%252C_%253Bfuj3b5eE2GnHaM%252CSfa97NMhTQlrMM%252C_%253B8ItNr4OZt2GI3M%252CrPG7T-PKqwdecM%252C_%253BoT7tR_P7gXw__M%252CK-Q79tmhxCQMlM%252C_%253BUJeirmLamOoJCM%252C4hDpQL0loNIXpM%252C_&usg=AI4_-kQfF9vI0MynPfUoPYm6FiTLbN5KFg&sa=X&ved=2ahUKEwjP7oDzyvHvAhUHPa0KHekKAEcQ7Al6BAgDEFg&biw=1103&bih=690&dpr=1.16#imgrc=SkID5EXPXcRQrM

How this helps
Eric

[Mike McGill]

Thank you Erick I think I'm on the same page as you this has been a long process but I think we are getting close

[Steve Huber Co-Admin]

Mike,
Before you throw $ at oil sensors, consider this. While the Aladdin shows flaky oil pressure readings, your dash gauge reads normal. Dave’s ET readout showed no oil pressure codes/issues. Since the Aladdin is reading the ECU, just as Dave’s ET does, that would seem to indicate a faulty electrical connection in the Aladdin circuitry and not an oil pressure issue. Maybe I missed it but I didn’t see any info on what code(s) the engine is displaying when the problem (check engine light) occurs. My suggestion is to quit chasing an oil pressure problem unless the codes indicate one.
Steve

[Eric Maclean]

Steve
Good point it could be wiring but if it is it would be between the oil pressure sensor and the ECM because the aladin is getting it's information via serial stream data supplied by the ECM and the ECM is setting the check engine light and a red light as well as derateing the engine as a result of the information coming from that sensor but your right there should be an accompanying low oil pressure code 46 for oil pressure  or very low oil pressure.
An oil pressure circuit fault broken or shorted wire should set code 24 if it's bad enough for the ECM to set a check engine light and red light derate.
Oil pressure circuit voltage too high or too low same code 24 you have to remember the code will only set if the voltage return is out of exceptable limits meaning zero oil pressure doesn't mean there is no signal return  but an open or shorted wiring would not fall under expected limits and would set the 24 code.
That said it would be prudent to check the wiring at the sensor through to the ECM for damage / corrosion which might create a resistance causing an erroneous reading but the problem is intermittent and that would lead me to think it's a faulty sensor rather than corrosion .
Eric

[Mike McGill]

Thank you Steve and Eric so two questions where would I see the code on the Aladdin? and I know where the two oil sensors are to check the connections But would you know the location of the ECM
thanks
Mike

[Eric Maclean]

Mike
The ECM is bolted to the side of the engine block as shown in the diagram in my earlier post
Eric

[Steve Huber Co-Admin]

Mike,
See pg 378 of your 05 Monterey Owners Manual for the procedure to read the engine codes. It's titled Engine Diagnostics.
Steve

[Eric Maclean]

Mike
Can you check for fault codes were looking for a code 46 ( low oil pressure)
In my earlier post #6 on this thread it gives a little insight into how to differentiate between oil pressure circuit and oil pressure signal related issues.

[Mike McGill]

Hi Eric and Steve I just made it home and used the Engine Diagnostics with the cruise control if I am looking at it correctly it was 8 flash then 4 more so 84 any Idea what that means. I will be able to dig into the possible bad wires tomorrow and will update you thanks again for your efforts

[Mike McGill]

not sure I am reading this but I think I am these are the codes I came up with
84
64
62
67
in this order

[Eric Maclean]

Mike the codes your showing are as follows
62- low coolant level warning
64-high intake temperature warning
67-aux output#7 current high or low
84-unknown
The low coolant is self explanatory (possible recovery tank leak)
For the high intake temp (check the radiator stack for dirt blocking air flow through the charge air cooler)
Dave may be able to give you more clarity on the last two

Hope this helps
Eric

[Mike McGill]

Thanks Eric I think the 84 is a speed sensor Dave had told me I was lugging the motor down and needed to drop down into 5th more often I will double check with him. I guess the good news is nothing shows up about low oil pressure. I did have the oil sensor unplugged when I ran this test but if I am correct the codes are in the computer and not real time do you know if that is correct?
thanks again