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RAS041

Hello, new O/O (will be upgrading to tractor ASAP) with plenty of tech. background making the jump to diesel. Working on my truck I effectively cleared all dtc except a barometric pressure out of range, intermittent, or erratic.

I recalibrated the ecm, thinking it somehow was reading wrong. it was the same calibration dt90275.15 that was in the truck. this is when the extra fault codes came on. just recalibrated ecm and the faults appeared. my def gauge that was working and full now has a light on and is at empty. just malfunctioning, the def temp sensor, fuel level sensor, and starter relay circuit are all throwing these Cricut above normal or shorted to high source as well as the barometric pressure data erratic, intermittent, or incorrect that started this whole thing.

I suspect the mechanic I sent the truck to may have changed some parameters to address the def faults they are almost identical and the man told me he needs a ton of cash to replace my turbocharger that was fine, but needed an actuator that I put in. Maybe my recalibration uncovered the root cause of the skewed barometric reading?. It is steady at that same 14-17 hg value.

Also, my sensors are getting about 7v. Is that going to skew my readings and return voltage, being that they are 5v circuits?. The sensor signal for Baro is .75v, a little high?.

I tested everything vs the map sensor. I actually bought twice to be sure, as I believe the Baro read is before I turn over engine at key on, then it reads intake/boost??. The reading was 14-17 hg which it should be closer to 30 if I'm not mistaken so I assumed it was out of range.

I refurbished my grounds. The battery neg. ground is (3) batteries in parallel. The ground on the frame rail is a post welded to the frame from factory. It has holes between welds and is rusty and crusty although I just hit it with the wire wheel last month. The nut and bolt have surface rust. Shouldn't it be good if it is tight and clean at connection?. I get 0.15ohms at that ground (not cranking).

I am getting voltage spikes up to 38v but they seem very fast and superficial, but the volts are all over between a couple volts and the 38v. The main power cables going to starter then alternator is stable at 12.5 keyed off but there's this four post, large 12v solenoid attached right under the windshield in engine bay with two thick positives cables and then two thinner 10-14 gauge wires. when they are attached, the large wire coming from behind the back of the block, not the alternator is the one that's spiking, as well as one of the smaller wires attached to it.

That's as far as iv traced it so far. When I disconnect the four wires, the truck still starts and the one large power wire is still spiking. So (I'm trying to figure out what feeds that hot wire) the smaller wire that was spiking is not spiking.

I notice at startup the voltage on dash in cab is jumpy between 11.5 and 14.1v. then settles at 14. the regulator in alternator is good. unit is brand new. I'm going to keep tracing the spikes. it has to be a bad ground, ground wire, or connector or a short in the positive cable.

Batteries are new and stable. Bad Bulkhead Module,? ECM?, ... what regulates the voltage besides alternator?.

I believe the solenoid allows the recharge volts into the battery bank maybe. It does charge but could a short cause overcharging and back feeding?. I can't stand electrical work.

I'm going to continue tracing it. I have replaced starter, alternator, batteries, trans cool lines, Fuel rail press sensor, Nox inlet sensor, Map sensor, coolant temp sensor, I put a new pigtail on new map sensor, replaced ecm ground strap to engine block, added a redundant ground from block to frame, put wiring back to stock as some sensor return lines were cut, and grounded to ac compressor, which was weird.

Thoughts?, Suggestions?.

Seems to be one underlying problem triggering all of this. My authority has been active a few months and I haven't moved a single load.

Between shady sellers, fake parts, scamming mechanics, parts dealers selling me parts according to my vin and not taking them back when they don't fit or work and having to become my own mechanic, I'm cooked at this point. LOL.

Is there a workaround since a lot of the faults are for inconsequential stuff like tank levels and temp of def tank? A potentiometer on the return signals to bring in range? a voltage regulator? I still must find the source before considering that crap. I don't want to. I must be able to run and earn. you could imagine all the tools, truck, parts, mechanic, and then cost of living I am being pushed in the direction of a work around temporarily. this has been going on for months. granted, much has been repaired. and i didn't know much about diesel trucks.