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DTC 1656

Brooklyn Tow said:
WAG= could the PCM be WG programed instead of TM programed= WAG

Or just have a BAD WG solenoid plugged in.....and it's making the PCM angry?
Click to expand...

Not clear on your acronyms. WG = Wastegate?

If so, Bill was clearly instructed that I had an ATT. He was staring at the program while I was on the phone with him and it's for an ATT, that is non-wastegate.

As noted in my prior post, I borrowed the wastegate solenoid from Colbythekid's '95. That solenoid is known to be working as he still has the vacuum operated wastegate AND I had changed the solenoid about 1.5 years ago when the original failed.

The only things left are the PCM and wiring. I further cleaned the ground connections to the passenger side frame today. They were already clean. I'll do the same at the firewall. Really running out of things to do here. This has become more challenging (though less problematic) than my rotatable CPS episode on the '95.
 
I didnt get out of the house today to check the truck wiring, darn playoffs and closet shelves needing installed, but will tomorrow. Must be some bad wiring.

I dont think there is any special programming to delete the wastegate solenoid, just changes the boost curve to better match the ATT to prevent boost code for too low boost, and he may increase the tolerance for how far off of the curve it can be before it boosts.
 
"I dont think there is any special programming to delete the wastegate solenoid, just changes the boost curve to better match the ATT to prevent boost code for too low boost, and he may increase the tolerance for how far off of the curve it can be before it boosts."

Bill said the same thing. If I make no progress with Bill, should I just drive up and meet
you to go over the wiring? Testing wiring is not my forte.
 
Circuit Troubleshooting

Alright, I attached my results of the pin tests. There are some diodes at work that allow readings on one direction vs other, so I wrote down all readings in both directions.

You will notice that some measurements are MegaOhms, MΩ, so if you werent getting that then you may have a shorting problem. You can print the attached off and take the same measurement for comparison.

From A to GND is just like measuring from the negative battery terminal to the positive terminal, which will show 0Ω, but OL the other direction. Otherwise it can get a reading to ground through the ingition switch when its not on.

I did not get an SES light when leaving the solenoid unplugged but I only drove it a mile or so. I gather from the cycling OL when the ign is on that the PCM is cycling it from full power to nothing trying to get feedback from the solenoid since its unplugged. I may have set a DTC eventually. What you could do, is just put a resistor between an ignition power source and the PCM wire that goes to the solenoid. Just cut the wire behind the glove box and put a reistor the same as the solenoid to an ign source. The solenoid is about 40 ohms. The OBD2 PCM pin is D14, which is in the blue 32 pin connector.

Let me know if you need any more info.
OBD2 Wastegate Solenoid Control Circuit.jpgView attachment WastegateHarnessOhms.pdf
 
buddy said:
Alright, I attached my results of the pin tests. There are some diodes at work that allow readings on one direction vs other, so I wrote down all readings in both directions.

You will notice that some measurements are MegaOhms, MΩ, so if you werent getting that then you may have a shorting problem. You can print the attached off and take the same measurement for comparison.

From A to GND is just like measuring from the negative battery terminal to the positive terminal, which will show 0Ω, but OL the other direction. Otherwise it can get a reading to ground through the ingition switch when its not on.

I did not get an SES light when leaving the solenoid unplugged but I only drove it a mile or so. I gather from the cycling OL when the ign is on that the PCM is cycling it from full power to nothing trying to get feedback from the solenoid since its unplugged. I may have set a DTC eventually. What you could do, is just put a resistor between an ignition power source and the PCM wire that goes to the solenoid. Just cut the wire behind the glove box and put a reistor the same as the solenoid to an ign source. The solenoid is about 40 ohms. The OBD2 PCM pin is D14, which is in the blue 32 pin connector.

Let me know if you need any more info.
View attachment 23884View attachment 23885
Click to expand...

Thanks Buddy! I was out fishing today, but may get to check this tomorrow AM as I don't need to be in the office until 1:00 PM.

attachment.php


attachment.php
 
OK Budday and AK are on for the chicken dinner.

Went out to do some Ohm meter testing with Buddy's chart, but did not get past the first test: A to B with ignition off. Initially got a reading of 16.03, but as I pulled the plug towards me it went OL. Tried to recover the initial reading, but only sporadically. I pulled the harness out of the tubing and noted it was wrapped in electrical tape. Started unwrapping that and one wire breaks out of the plug. Then the pink wire breaks about an inch away from the plug. If it wasn't a wiring problem, it is now.:rolleyes5:

Running out of time and don't need the truck at the moment (NAPA did not have it), so I ordered the plug from Rock Auto:

ACDELCO PT374 Turbocharger Connector $ 18.74 $ 0.00 1 $ 18.74

Fingers are crossed that this was the problem. Bill Heath seems to think that was the problem too, even before I went out and broke it.:eek:
 
The new wastegate solenoid plug arrived today. I crimped
it into place and drove the rig up to Big Bear Lake. So far
no codes. Still have the Security light coming on. Tried another set of three 5 minute cycles, but the Security light still returns on after some acceleration or revving of the engine.

Following are pics of the old and new plugs:

IMG_0396.jpg


IMG_0394.jpg
 
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Glad you were able to find this electrical gremlin. Sometimes it can be really hard to find, and its too bad the shaking the wires the first time didnt show it. We would have licked it one way or another, and you also got an updated PCM out of it.

I am hoping to get up to Big Bear myself 18-21 Feb.
 
I am a neophyte on electrical testing. My initial testing did not reveal the problem because I did not know what I was looking for. Once you posted your results in a chart, I could do the testing in a methodical way and the answer soon became obvious.

I will put that Feb 18-21 weekend in my calendar and try to be up in Big Bear, though no promises. Would love to meet up with you. I suspect that weekend coincides with a waxing full moon phase, which is a peak time for trophy bass fishing and that trumps everything, including 6.5 TDs.
 
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