Pressure washed and now in limp mode!?

StuartZickefoose · **Joined:** Wed Mar 25, 2020 1:23 am **Posts:** 6

Hey all! I posted this over in the KJ forum but i goofed and didnt see the diesel specific forum ....reposting here hoping for insight!

StuartZickefoose wrote:

Hey All!

first time post here, but been on forums for aircooled VWs since 08. Been fixing cars fir over 12 years now, Honda factory trained tech...blah blah. Makes me sound smarter then i am

Just got my hands on a 2005 liberty CRD for my little sister. One owner, 113k miles. Minimal issues so far...replaced parking brake shoes, found a previous patch on transmission cooler lines and tightened the leaking hose clamps...then pressure washed the engine to clean up the mess it had left.....

Only to end up with a CEL!

I have a P0652 that sets instantly on key on at all times. Cant make it go away.

As a result, p0193, and limp mode, which causes p0299. (Fuel Pressure sensor reading high, goes to limp mode, boost limited causes low boost code)

Prior to washing the engine it ran fantastic. Great power, smooth and quiet. No issues besides cooler line leak.

I have cleaned the grounds behind brake booster (1) top of fender (2) and under headlight (1post 2 wires) which i moved to the brake boost ground pin because they were so badly corroded i couldnt get the bolt out.

I have wiggled and dried out the connectors on the pressure sensor at the rail, the computer by the left fender (rear of battery) (which was dry and clean contacts) and the computer on the right fender.(which was full of water after wash)
Replaced one 10am fuse under the hood that was corroded also.

I found the connector on the right side of the fuel filter to be melted and funky, cleaned best i could and reinstalled. No issues up to this point but once the p0652 code goes away its on a to do list. Thats for the fuel heater/water in fuel sensor, right?

I have not pulled wires off the FCM (forward and under the battery) to see what they look like yet.

Im running out of ideas, i refuse to buy parts until its a confirmed failure. So i wont just toss new sensors on it.

Considering it says reference voltage is low, is there a powered wire i can check for the 5v reference?

The sensor on the rail, not solenoid, sensor, is getting 5v. Its returning 4.9v roughly. Plugged in. Not totally sure i tested that one correctly...

Read through the other 4 threads with these two codes (0652, and 0193, the two that come back) mentioned, all others have either a no start or major running issue. Mines smooth and limp mode. Starts every time, no changes otherwise.

Any suggestions?

turblediesel · **Posted:** Mon Jun 01, 2020 12:20 pm

I can't help with your codes but your fuel filter head should be replaced with a metal version that looks identical. ID Parts has a kit. Air will get into the fuel flow there and cause driveability issues.

WWDiesel · **Posted:** Mon Jun 01, 2020 12:45 pm

From an older post by Flash7210, but still pertinent to your issue.

P0652 is sensor reference voltage low.
Does not specify which sensor.
According to the book it could be:
INTERMITTENT DTC
5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
CRANKSHAFT POSITION SENSOR
BOOST PRESSURE SENSOR
FUEL PRESSURE SENSOR
ENGINE CONTROL MODULE

Click here to read through whole thread

Billybob · **Posted:** Tue Jun 02, 2020 2:01 am

Good chance you got water into one of the sensors...crank, cam, FCM....which is very exposed, Map etc. :shock:

Also maybe the ECM although they it is fairly well sealed.

I would take a hairdryer or heat gun...on Low Heat....all over the engine bay especially all the sensors noted above. Then leave the hood up facing the sun ..if you have sun at the moment!

You can remove the two connectors on the ECM without disconnecting the battery...several Fault Finding exercises call for this to be done so that voltages can be measured at the ECM pins.

TCM should also have the connector blown with hot air.

On the ECM you slide the connectors off...the 2005 Jeep KJ Service Manual shows you how.
The cables coming into the rear of the ECM connectors have a plastic cover which slides off...I would remove these covers and blow hot air over the rear of the connectors.

Before buying my 2002 Export CRD I had a POS Diesel Land rover Freelander.
Took it in for a service....two miles down the road after picking it up it ground to a halt with steam and sparks coming off the ECM connector.

Had to have it towed back to Dealer who tried to wipe his hands of the problem but he eventually had the ECM repaired.
I am very wary of using a High Pressure cleaner on my engine bay...I wrap most electronic components in plastic and avoid those areas! :wink:

StuartZickefoose · **Joined:** Wed Mar 25, 2020 1:23 am **Posts:** 6

Couple of updates i forgot to mention in my haste to repost...my apologies!

Ive tested and found a fauling fuel pressure sensor (not regulator) and replace with the GM version for $20 vs $300. No change, but old sensor HAD failed (resistance was very out of spec)

The pressure wash was mid February. Its been driven nearly two full tanks in limp mode in hopes of drying things out, along with a air compressor to all computer connections, tcm, and FCM and ECU. All are now dry.

All grounds i could find (behind headlight, driver firewall and under battery) were absolutely nasty. Repaired cleaned and secured.

Battery swapped out for a newer one from a car that was just totalled (not new but plenty of kick) vs the original 2008 red top (that still starts my acura fine...)

Known fuel pressure drop when sitting causing very hard starts after say a week of sitting. Hand prime and it kicks over a bit sooner so eventually a lift pump install is in the works, but not until this issue is sorted.

I know it needs a fuel filter as i dont have a last replaced date on it.

This sensor reference voltage i have at the instant the key is on. Engine on or off, so i know its a hard failure, not intermittent. Ive got zero luck shaking down the harness to change any results. Checked behind fuel filter and shook and eyeballed harness there, didnt get too close but no change.

Was going to test the crank sensor however, two thing (for my sanity)....tach runs if alternator so the crank sensor wont affect tach like a gas car, correct?
And two, would it start at all without a crank sensor? I would simply unplug and test that out but its such a pain to reach i havent tried it yet (on my list to do this week)

I have until next friday or i admit defeat and let a local diesel shop handle its diag. Ive pressure washed dozens of new and old engines and never had issues (from 60s to 2 year old cars) so this threw me when it had an issue. I knew when i got it it was having an intermittent no start and limp mode issue, so it was itching ti fail already, so i dont feel all that responsible for finding an existing issue vs breaking it...but nonetheless, i wanna get this sorted asap.

Thank you all for the help! I last played with it two months ago and im just getting back to it so im having to refresh my memory as i go.

Leaning towards the crank sensor (saw that thread yesterday btw, thanks for the link!) but just havent got a chance to test it yet.

The secondary hard start issue im nearly positive is the fuel having air in it but failing and tossing a code key on engine iff shows theres a bigger issue to me.

gollygeemister · **Posted:** Tue Jun 02, 2020 9:25 pm

Check the ground on the passenger fender. Down below the PS reservoir.

StuartZickefoose · **Joined:** Wed Mar 25, 2020 1:23 am **Posts:** 6

gollygeemister wrote:

Check the ground on the passenger fender. Down below the PS reservoir.

Bit surprised i missed that one, but i got it off and cleaned and reinstalled. (Wasnt too bad) no change. Cleaned dirty MAF sensor also, no change. Digging now to find the crank and cam sensors and test them.

StuartZickefoose · **Joined:** Wed Mar 25, 2020 1:23 am **Posts:** 6

Any other suggestions? I cant fathom it being a crank sensor because it actually runs, and every crank sensor or cam sensor ive had fail kills the engine completely.

Ive cleaned every ground i could find and fixed quite a few nasty ones, where are my computers getting their 5v reference signal from? Is there a pin on the ecu i can check for a 5v output and again at the sensor?

Going to double check readings of 5v and ground at the fuel pressure sensor, cant remember my findings...

Pressure washed and now in limp mode!?

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