DDEC 4 Code 34 Turbo Boost Circ Low

[encantotom]

hi all,

just running my rig in the driveway i have started getting a check engine light with the error of Turbo Boost Circ Low on the prodriver. code 34.

the turbo boost sensor is part number 23522322 and is in plain site on the exhaust manifold on the passenger side of the engine right above the DDEC4 ECM.

i have found some troubleshooting for it online for a DDEC3, but i think the sensor is different on a DDEC3 than it is on my ddec4.

do any of you have the dde4 troubleshooting manual?

or have any experience with this error?

i am guessing it is a wiring or sensor issue and not a turbo issue from what i can read about it.

any wisdom?

a sensor is like 75 bucks so not expensive to try.

thanks

tom

[tuga]

Tom,

I had that error for about 2 years! It never amounted to anything and it has not re-surfaced in the last 3 years.

I would ignore it.

[davidmbrady]

Hi Tom,

I don't have any experience with code 34, which the manual has listed as "Turbo Boost Pressure Sensor Input Voltage Low", but I do know that replacing the turbo boost sensor is more than trivial. It seems that over the years the cadmium plated bolts holding the sensor in place have corroded with the aluminum of the intake manifold. You definitely want to try soaking the bolts in penetrating oil for a few days before attempting to remove them. A couple of taps on the head of the bolt may be enough to break the bond. Even then, a sheared bolt is almost certain, in which case removing the intake manifold to gain clearance to insert a heli-coil may be necessary.

David Brady
'02 Blue Bird, Wanderlodge, LXi, NC

[encantotom]

hi david, thanks for the tips on the bolts. they are small. i started spraying them with a penetrating oil.

if the bolts are short and just go into the manifold, then i think it would be fairly easy to get them out.

am i missing something?

take a look at the pictures of where it is on mine in relation to the engine compartment.

tom

[davidmbrady]

Hi Tom,

I'm envious of the engine access that you guys enjoy with your Newells. My coach doesn't have the access to the side of the intake manifold that yours does. The bolts don't go all the way thru the intake manifold, so if you happen to shear one while trying to remove it, it should be simple for you to install a heli-coil. For me, I have to remove the manifold.

David Brady
'02 Blue Bird, Wanderlodge LXi, NC

[encantotom]

i put a penetrating oil on them for a couple of days. they came out very easily. you have to be careful because there is an o ring that can fall out. i cleaned it all up and sprayed contact cleaner on the weatherpak plug and the connector. i put it back in and ran it for 5 min or so and no error code. will see if that really fixed it or not as time goes on.

i could change the sensor in 3 minutes if needed.

tom

[Genman]

Tom
Before you spend any $, check your connections from harness to ECM. These are Delphi connectors and extremely efficient at keeping dirt and corrosion at bay however, corrosion (even not visible to the eye) can occur. These signals are quite low and a voltage drop across the terminal will cause the ECM to display a fault. In the case of higher energy signals, the injectors can experience long response times and not fire at all. Remove the 4/5 wire connectors by carefully spreading the latch catch and pulling, in the case of the 10 and higher wire count connectors there is an 8mm (if my memory is correct) fastener in the center. Unscrew it and remove (do not over tighten when reassembly, you do not want a broken terminal body). Spray with a contact cleaner and apply a terminal grease then reconnect.
Hope this helps
Gordon

[encantotom]

thanks gordon,

i found a used sensor to have as a spare for 20 bucks but i hope cleaning the plug like i did will fix it. seems to have just sitting in the driveway but time will tell.

thanks again,

tom

[encantotom]

well it is popping up again. i changed out the sensor and it didnt change anything. so time to trace the wiring out i guess. i have posted on a truckers site about engines to see if they have any wisdom as to what it causes.

tom

[encantotom]

an update.

on june 1st i was still getting the code when sitting in the driveway. michael and i took the coach to go get the new tires put on it. we got about a quarter mile and the service engine lite came on. michael was monitoring the vmspc and saw the same code for turbo boost circuit voltage low come on. then about fifteen seconds later the stop engine light came on and i lost power as it went into safe mode.

i got to the center lane on a surface street and turned it off and then back on. no codes. and from that point on, no more codes. i have driven it probably 75 miles since then in the city and on the freeway and no codes. running in the driveway, no codes. yesterday at the bus shop i had the engine guy put his scanner on. he saw the old codes but we couldnt get it to throw a code. he suspects the sensor was bad and until i drove it the ddec didnt get to reset properly somehow. since i bought a used sensor on ebay he suggested to put a new one on so i will order one.

tom