Jeep Commander Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hi, I have a 06 Commander 4X4 I had already changed the gas cap but was still having problems. 3 times to the shop for evap leak. Replaced smog pump 2x's and the sensor 1x now the evap purge solenoid. Constant check engine light ON. Was wondering if anyone else had this same problem? All before 56,000 thousand miles. Today they replaced solenoid and replaced a trans electrical connector. (5) days after replacing the pump again.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #3
Yes thank god. I bought the extended 2. This one was free tho due to constant problems. It seems like alot of people were having the same problem. ie gas cap and same codes. They had to go over mine with a "fine tooth comb" to finally get it right.
 

·
Registered
Joined
·
2,387 Posts
just make sure you keep all documentation of repairs if it goes out of warranty and same issues arise! Good luck and Welcome to the Forum!
 

·
Moderator
Joined
·
2,248 Posts
I have a little bit of information that might cast some light on the issue.

When I was talking to the owner of the company that is installing my second gas tank, he told me that the reason for the check engine light when the gas cap is not tight is because there is a small compressor that pressurizes the gas tank and compares the pressure reading to the amount of gas indicated in the tank. If the readings do not corelate the computer throws the code and lights up the check engine light.

This fellow installs gas tanks all the time and I think he definitely knows his business. He also said that he might have to install ball valves in the fill and vent line to avoid the code with two tanks. He also said that the code for the gas cap would not hurt anything and could be erased by disconnecting the battery ground and reconnecting.
 

·
Registered
Joined
·
1,352 Posts
.... there is a small compressor that pressurizes the gas tank ...
I've never heard of this before ... maybe that's just the way he explains it to the us non-mechanics ... there's nothing in the Commander parts list that indicates any small compressor for the fule tank.

I suppose it could be part of the fule pump assembly? ... but it seems unlikey.

There would be several a presure sensors for fule system and the fuel itself builds up presure on it's own all the time.

Of course, I've never done any volume of work myself on the Commander :) .. and I'm assuming the parts catalogue shows EVERY single part ... but that seem a reasonable assumtion to me.
 

·
Moderator
Joined
·
2,248 Posts
I went thru the manual and found this:

GAS CAP INDICATOR
DESCRIPTION
A gas cap indicator is standard equipment on all instrument clusters. However, on vehicles equipped with the
optional diesel engine, this indicator is electronically disabled. The gas cap indication appears within the reconfigurable
dot matrix Organic Light Emitting Diode (OLED) display unit. The gas cap indicator consists of a textual
CHECK GAS CAP message which appears in place of the compass/trip computer information in the dot matrix
display.
The dot matrix OLED is soldered onto the cluster electronic circuit board, and is visible through a window with a
smoked clear lens located on the lower edge of the tachometer gauge dial face of the cluster overlay. The dark lens
over the OLED prevents it from being clearly visible when it is not illuminated. The gas cap textual message
appears in the same blue-green color and at the same lighting level as the compass/trip computer information when
it is illuminated by the instrument cluster electronic circuit board.
The gas cap indicator is serviced as a unit with the OLED in the instrument cluster.
OPERATION
The gas cap indicator gives an indication to the vehicle operator when there is a gross leak detected in the onboard
fuel vapor recovery system. This indicator is controlled by the instrument cluster logic circuit based upon
cluster programming and electronic messages received over the Controller Area Network (CAN) data bus from the
Powertrain Control Module (PCM).
The gas cap indicator function of the reconfigurable dot matrix Organic Light Emitting Diode (OLED) display unit is
completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate
when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit.
Therefore, the OLED gas cap indication will always be OFF when the ignition switch is in any position except ON
or START. The instrument cluster will turn ON the gas cap indicator for the following reasons:
² Gas Cap Indicator Lamp-On Message - Each time the cluster receives an electronic gas cap indicator
lamp-ON message from the PCM indicating there is a gross leak in the vapor recovery system, the gas cap
indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message
from the PCM, or until the ignition switch is turned to the OFF position, whichever occurs first.
The PCM continually monitors the on board vapor recovery system to determine whether there are air leaks in the
system. The PCM then sends the proper lamp-ON or lamp-OFF message to the ElectroMechanical Instrument Cluster
(EMIC). If the EMIC turns ON the gas cap indicator due to a monitored gross leak in the vapor recovery system,
it may indicate that the gas cap has been removed or is improperly installed.
For proper diagnosis of the on board vapor recovery system, the PCM, the EMIC, the CAN data bus or the electronic
communication related to gas cap indicator operation a diagnostic scan tool is required. Refer to the appropriate
diagnostic information.



Maybe the compressor that he was referring to is the vapor recovery pump.
 
1 - 7 of 7 Posts
Top