I realize this is an old topic but new to me as I never had an issue before in 50K miles. CRD has 87K miles , GDE Eco tune and exhaust. Everything else is stock. Check engine light recently went on and multiple cycles has not turned it off. Had codes ran and P1252 & P0299 came up. Should I start with the Vacuum reservoir solenoid first? What about the ASD relay? Still have original hoses but they don't sound like they are leaking.

Sounds like one of your vacuum solenoids went bad.
It's usually the bigger one and it starts making a loud buzzing noise when it goes bad.

_________________
U.S. Army Retired

P1252 Jeep Description
Possible causes
- Faulty Vacuum Reservoir Solenoid
- Vacuum Reservoir Solenoid harness is open or shorted
- Vacuum Reservoir Solenoid circuit poor electrical connection
The Engine Control Module (ECM) detected a short to ground on the Vacuum Reservoir Solenoid control circuit

_________________
Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

Trace the vacuum line back from turbo to boost evm (has little air filter on bottom and blue isolator), then to the reservoir evm (all black). Take the vacuum supply off the black evm and plug it into the boost evm in the port labeled "vac". This by-passes the on/off evm and should restore boost and drivability while you order a new black evm.

_________________
Providers of wholly developed aftermarket solutions for the KJ CRD.
(248) 977 - 9531

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

I just removed the vacuum hose and bypassed the solenoid. When I removed the hose I could here the vacuum release. Does this indicate the vacuum solenoid was still functioning?

Also seems to indicate the hose is good
- raise the VVT linkage, place your fingertip over the hose barb, release the linkage: if diaphragm is good, linkage will hold
- place your fingertip over the hose-end with engine running: if it makes a hickey on your fingertip, hose is good, no leaks

However, the solenoid vave might not leak, but the coil is bad, not energizing the solenoid valve - or, after all these years, coil is good but the solenoid shuttle may refuse to travel = no valving action

This is always a probem with PWM-actuated devices

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

I bypassed the vacuum solenoid by moving the vacuum line and it seems to run better. Which solenoid needs replacing?

Turbocharger Vacuum Modulator 52109543AA or Vacuum Solenoid 4606226AC

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

I know this post is very old but i stumbled across it and am having a very hard time figuring out what green diesel engineering stated in one of the threads. it was something about by-passing the vacuum line coming off the turbo. i'm sorry but his description isn't very helpful. can someone please help me with a more clear description of what hose gets pulled from where. thank you. i've ordered both pn: 52109543aa and 4606226ac

From one of my older posts:
You can temporarily bypass the No. 2 item, vacuum reservoir for a test as follows:
Remove hose from "A" location and connect it to "B" location for test.

Turbo Vacuum solenoid test procedure

Failure of the vacuum reservoir solenoid (a.k.a. solenoid secondary runner valve per the parts fiche PN(PN 4606226AC) ) can produce several MIL/CEL codes and result is turbo boost problems. A temporary solution and diagnosis is to bypass that solenoid by rerouting vacuum lines as in the picture below:

By disconnecting the hose from where the red arrow is (location A) and re-connecting it where the yellow arrow is (Location B port on modulator). If that solves the problem then leave the hoses in the new/temporary configuration and order a replacement solenoid. In the interim the vehicle may be driven; the CEL will remain until you replace the on/off solenoid. The only benefit that part provides is overnight storage of vacuum in the plastic reservoir so the turbo has vacuum immediately during the start. Without it you have a 2-10 second wait before the engine vacuum pump evacs the lines enough for the turbo vanes to move. Once the replacement solenoid is installed put the hose(s) back the way they were originally.

GDE's writeup for this says "By-passing of the on/off solenoid is very straight forward. Trace the vacuum line output from the black plastic reservoir to the input of the on/off solenoid. Remove this vacuum line and plug it directly into the turbo EVM on the port labeled "VAC". The turbo EVM is the one with the blue rubber isolator and vacuum line running directly to turbo."

Also, you should probably trace the small plastic vacuum impulse line from the turbo vane modulator to the turbo van controller for a melted, collapsed, or cracked vacuum line as in this post at: viewtopic.php?f=5&t=61240
Several including myself have found problems with this line!

_________________
Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

WWdiesel thank you so much for that. i now know where i was confused with gde's description. i'll be trying that later today. once those parts come in i will replace that hose you suggested.
i'm only getting the P0299 code and one of those vacuum parts was making the humming noise, up until last week. and thats when we started getting no low end boost. thanks again.