Turbo shuts off - Overboost

fetam

New member
So I have a 2004 Dodge Sprinter 2500 with 170,000 miles on it. I'm having an over boost problem according to my MaxiDiag Elite MD802 - Autel scanner. Shuts off the turbo until I clear the code.

Code: "2526 Component Y100 (Boost Pressure Regulator) is faulty. Open Circuit"

I put in a new aluminum resonator on about a year ago when I got the van just to not have to ever have a broken plastic one. I live full time in the van and didn't want to get stuck somewhere.

Also don't have any leaks in any hoses that I could find with soap and water sprayer.

Is there a way to test the actuator myself? What about the pin out for the plug? Can I test that to see if I'm not getting the right voltage or something?

I'm a pretty handy guy and know most things about engines but diesels and turbos are a little new to me.

Where do I start? I appreciate any advice!
 
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autostaretx

Erratic Member
Both 2004 and 2006 service manuals are available here: http://www.diysprinter.co.uk/reference/

Let's look at the 2006: http://diysprinter.co.uk/reference/2006-VA-SM.pdf
and the 2004: http://www.diysprinter.co.uk/reference/2004-VA-SM.pdf
(there are other 2004 sub-system manuals at that directory)

Section 8W is/are the wiring diagrams, one of the last sub-sections are the connector pinouts.
The actuator is shown in section 8W subsection 30 as the "boost pressure solenoid"
(fig 8w-30-14 in the 2006 manual, probably the same in the 2004)

I think the boost actuator solenoid is simply that: a coil of wire.
So it should response to an ohmmeter test across the unit.

The driving circuit is undoubtedly PWM (pulse width modulation), so a voltmeter would give a hint that it's being pulsed. but not a great idea of the percentage of boost being requested (proper scanners can command a specific positioning from 5% to 95%). An old analog "needle" voltmeter would do better.

IF you unplug the MAF, the boost solenoid should move. Quicky test.

Overboost sounds more like the actuator (solenoid) is being slow to release the vanes (i *think* the no-power state is the turbo NOT engaged (i'd sure hope)).
So it could be a sticky/dirty mechanical linkage between the actuator and the turbo itself.
Although the "open circuit" sounds like either a sick solenoid or wiring harness damage.

A weak point in the harness is behind the fuel filter .. the harness is strapped to the engine block, forcing a very tight bend in the cables that is prone to vibration-caused internal chafing and short circuits. Release the tie wrap, fondle the harness and see if things change.

The signal the boost actuator is getting is shown here:
http://www.diysprinter.co.uk/reference/T1N_service_scans/238Scope.jpg
and here: http://www.diysprinter.co.uk/reference/T1N_service_scans/239Scope.jpg

(and http://www.diysprinter.co.uk/reference/T1N_service_scans/ is chock-full of training information)

good luck
--dick
 
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Midwestdrifter

Engineer In Residence
That code points to a wiring fault at the turbo actuator. Or possibly a bad actuator. Give the wiring, connector etc, a good look.
 

fetam

New member
So I cleared the code and took the boost pressure sensor out (driver’s side hose) and there was a little oil underneath. O ring doesn’t look that great but cleaned it up and put back together.

I disconnected actuator arm and the actuator didn’t move but turbo arm did. No rust or corrosion at all. I’m guessing that means the actuator isn’t stripped? Hooked up arm to turbo again.

Cleared code and while running I watched actuator arm and it moved smoothly while wife revved engine. disconnected mass airflow and actuator moved like it was supposed to. Then threw code again. Bahhhh!

Got underneath and disconnected actuator while engine was running. Then reconnected while running. Arm moved and running normal. I’m thinking it has to be the actuator wiring/plug. Gonna try and drive close to a town. We are in the wilderness and about 100 miles to the closest auto parts store.

Can I buy this plug to replace? Or is it part of some big harness I have to buy?
 

Midwestdrifter

Engineer In Residence
Don't shotgun parts. If you can cause the code by wiggling the harness somewhere, then you know where to look. It may not be the plug. Have you checked the wiring harness around the fuel filter for chafing?

The next step would be to unplug the main harness from the ECM/ECU. Then you can ohm out the wires that run to the actuator.
 

fetam

New member
I did unclip the 2 big zip ties holding a harness behind fuel filter, close to the steering knuckle. Wiggled them around. Not sure if it was the right harness or not.

Where is the ECU? Under driver’s seat or under dash?
 

autostaretx

Erratic Member
Where is the ECU? Under driver’s seat or under dash?
Page 8E-6 of the 2006 manual:
(plus Fig 22 from the locator diagrams at the end of 8W)
It's behind that cubby hole to the left of the steering wheel:

ECMfig4.png

REMOVAL
(1) Disconnect the negative battery cable.
(2) Disconnect the ECM harness connectors (Fig. 4).
(3) Grasp ECM and pull down firmly to release ECM from the retaining bracket tensioning springs (Fig. 4).
INSTALLATION
NOTE: THE ECM MUST BE PROGRAMMED TO SUPPORT THE VEHICLE OPTIONS PACKAGE.
(1) Position the ECM into the guide of the retaining bracket (Fig. 4).
(2) Carefully push the ECM in to the bracket until the bracket tensioning springs engage (Fig. 4).
(3) Connect the ECM wiring harness connectors (Fig. 4).
(4) Connect negative battery cable
---------------------

That said, the Sprinter can be driven without the turbo functioning, (it just has half its normal power)

Oil in the air plumbing (as removal of the boost pressure sensor revealed) is normal.

--dick
 
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