TOP TECH QUES­TIONS

Diesel Power - - Contents - W. S. Han­cock via tele­phone

QUES­TION: The 6.6L Du­ra­max LLY engine in my ’04 GM pickup has 105,000 miles on it and a Check Engine light is show­ing. Af­ter scan­ning the ECM, I found out the prob­lem is as­so­ci­ated with di­ag­nos­tic trou­ble code P0045 (boost-re­lated is­sue con­cern­ing the tur­bocharger’s vanes). I delete it, and it comes back af­ter a few hun­dred miles. My re­pair shop says the prob­lem is more an in­con­ve­nience and not worth the ex­pense of in­stalling a new tur­bocharger. I am plan­ning a boat­ing trip up to Alaska and don’t want any ma­jor prob­lems. Would this cause a break­down or some­thing close? Ad­vice on how to han­dle this is ap­pre­ci­ated.

AN­SWER: When­ever a di­ag­nos­tic trou­ble code is trig­gered, try­ing to de­ter­mine its cause and mak­ing the ap­pro­pri­ate re­pair is al­ways the best way to pro­ceed. Ig­nor­ing DTCs for too long is not rec­om­mended. The code in your truck’s ECM, DTC P0045, could per­tain to the turbo’s vanecon­trol so­le­noid, which re­ceives a com­mand from the ECM to change the an­gle of the vanes ac­cord­ing to the load placed on the engine. The con­trol so­le­noid has two cir­cuits—High and Low. The ECM com­mu­ni­cates with the so­le­noid to con­trol the po­si­tion of the turbo vanes. Chang­ing the vane an­gles in­creases and de­creases boost. If the ECM sends a sig­nal to the so­le­noid and the so­le­noid doesn’t re­spond cor­rectly within 1 sec­ond, the ECM senses there is a boost is­sue and trig­gers DTC P0045 and/or P003A. The causes for the code are nu­mer­ous: a bad wire to the con­trol so­le­noid, a bad or stick­ing con­trol so­le­noid, or stick­ing tur­bocharger vanes. It could also be ac­ti­vated be­cause boost pres­sure is bleed­ing from a leak in the in­ter­cooler boots or tubes. Usu­ally, the cause is di­rectly re­lated to car­bon/soot buildup ei­ther on the end of the boost-con­trol so­le­noid or around the vanes in­side the turbo. To get to the root of the prob­lem, the first task is to use a scan tool and run a di­ag­nos­tic on the so­le­noid by turn­ing it on and off. Ac­cord­ing to GM’s 6.6L Du­ra­max ser­vice man­ual, the vane-po­si­tion sen­sor’s pa­ram­e­ters should be 95 to 97 per­cent when it’s on, de­creas­ing to al­most 0 per­cent when it’s off. A stick­ing so­le­noid can be re­moved, cleaned, and re­in­stalled, while a defective part is eas­ily re­placed. If the so­le­noid checks out, then pres­sur­ize the boost tubes to the in­ter­cooler to see if there are any leaks from bad boots or loose clamps. If that part of the sys­tem is good, then the prob­lem is likely as­so­ci­ated with stick­ing turbo vanes, and that usu­ally re­quires re­plac­ing the ’charger, be­cause it’s very dif­fi­cult to thor­oughly clean the vanes. Any residue left be­hind will act like a mag­net, quickly at­tract­ing soot, so the same prob­lem would re­turn months later. A good diesel shop can per­form all the tests to di­ag­nose and rem­edy the prob­lem.

Di­ag­nos­tic trou­ble code P0045 and/or P003A can be caused by nu­mer­ous is­sues re­lated to tur­bocharger vanes, in­clud­ing a bad wire to the con­trol so­le­noid or a stick­ing so­le­noid or turbo vanes. It could also be trig­gered be­cause boost pres­sure is bleed­ing...

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