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Discussion Starter · #1 ·
As mentioned 2002 MT 4x4 model with 168k on the odo, story started when truck was taken to dealer for same problem. Apparently vehicle had exactly these same symptoms, it was "repaired" after several months. Within a couple of months the symptom (no boost, no communication) returned. When the customer called the dealership, he was informed that they were not interested in working on the vehicle again! Customer brought the vehicle to the shop and after a cursory look I asked to see the invoice from the dealership, it was basically an un-itemized invoice stating the truck had been repaired with no parts or labor breakdowns. Roughly $1800.00, So much for that...

Back to the present, the truck starts right up and will take throttle but runs like an old 6.2 Chevy non-turbo diesel. Zeus scanner will plug in and recognize the vehicle, it will not read vin and when you go to data there are N/A readings across the board. There are no DTC's. We have good grounds at DLC terminal 4 and 5 and 12v at terminal 16. Measuring from ground to terminal 6 I get 5.0v and on terminal 14 it is 4.5v. It was my understanding that the serial data terminals should add up to 5.0v between the two, Like 2.7 on 6 and 2.3 on 14 where the sum equals 5.0v. We have checked the connector on the fuse box and have literally ohm the harness from end to end.

The wiring diagram shows terminal 6 goes straight to the PCM SCI receive connection and Terminal 14 goes to ECM SCI receive connection.

Wondering is anyone has seen this or has an idea of how to proceed without throwing parts at it, I did send ECM out to have it checked and there was no improvement.

Thanks for reading.
 

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I believe most data is not available on 2nd gen. But you should b e able to pull codes and clear them. On an 02 you can also try the key trick for codes, but a scan too is usually better. Make sure the ground wire from the PCM to the fire wall. Remove it and clean wire and firewall, and do the same to other grounds like under the pcm and battery cable ends.

You said you had the ECM tested, so I assume the Wait to start light comes on every time you turn the key to ON???

You might replace the MAP sensor just because it could cause that issue and is a voltage sensitive sensor. Also check all sensor harness plug connections for loose connection oar corrosion and bad connection?
Have you checked the APPS voltage. Should be 5v input and idle on pin 3 should be about .5 at idle and smoothly graduate to about 3.8b at WOT.

Check closer harness connections for corrosion etc and the grounds an connections on the bottom side of the PDC. Lift pump fuel pressure is?? Fuel filter?

Waste gate? other exhaust? Boost hoses slit? What kind of stuff do you usually work on?
Almost all running issues are related to ECM not Pcm except some voltage issues.

Does it ever throw a CEL when it won't take off?
Breaks in wire inside the harness have been found before. Any 5v supply wire that is not at least 4.8v has a problem. Trace them back t source and see if it is corrosion or bad from the source(ECM or other component.

NO communication is often the commuter on one or the other that is bad and not commutating. IE, bad circuit in the VP, ECM, PCM, APPS, Central timer, Try codes again, Use key or a different can tool if you have to. Do not expect more than codes.
 

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not "throwing parts at it" but have you tried a cheap replacement MAP sensor, or resistance test? like... the thing that controls the boost.... to my knowledge the turbo is pretty mechanical, limiting factor must be a sensor or something
 

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Discussion Starter · #4 ·
I believe most data is not available on 2nd gen. But you should b e able to pull codes and clear them. On an 02 you can also try the key trick for codes, but a scan too is usually better. Make sure the ground wire from the PCM to the fire wall. Remove it and clean wire and firewall, and do the same to other grounds like under the pcm and battery cable ends.

You said you had the ECM tested, so I assume the Wait to start light comes on every time you turn the key to ON???

You might replace the MAP sensor just because it could cause that issue and is a voltage sensitive sensor. Also check all sensor harness plug connections for loose connection oar corrosion and bad connection?
Have you checked the APPS voltage. Should be 5v input and idle on pin 3 should be about .5 at idle and smoothly graduate to about 3.8b at WOT.

Check closer harness connections for corrosion etc and the grounds an connections on the bottom side of the PDC. Lift pump fuel pressure is?? Fuel filter?

Waste gate? other exhaust? Boost hoses slit? What kind of stuff do you usually work on?
Almost all running issues are related to ECM not Pcm except some voltage issues.

Does it ever throw a CEL when it won't take off?
Breaks in wire inside the harness have been found before. Any 5v supply wire that is not at least 4.8v has a problem. Trace them back t source and see if it is corrosion or bad from the source(ECM or other component.

NO communication is often the commuter on one or the other that is bad and not commutating. IE, bad circuit in the VP, ECM, PCM, APPS, Central timer, Try codes again, Use key or a different can tool if you have to. Do not expect more than codes.
Thanks for the reply, check engine light is not on and no DTC's present ever, using a Snap On Zeus scanner and as I mentioned all data readings are N/A on screen. Literally the value listed on each PID is N/A. All grounds have been cleaned twice, fuel pressure is within spec, wait to start light comes on momentarily. I will reverify 5v reference to applicable circuits as well as APPS function. As mentioned, the truck starts and runs fine, it just won't make boost even though the turbo is actually building boost on a pressure gauge. I actually think I have a good test map sensor but never thought to try it for this data loss issue. I checked all computer data lines with DVOM but have been fooled by bad connectors before, I am going to labscope the serial data terminals in a minute once I get a chance. Super busy on top of it all.

We work on all brand gas and diesel on up to medium duty stuff.

Thanks again.
 

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Discussion Starter · #5 ·
not "throwing parts at it" but have you tried a cheap replacement MAP sensor, or resistance test? like... the thing that controls the boost.... to my knowledge the turbo is pretty mechanical, limiting factor must be a sensor or something
Gonna do that right now. turbo is building boost, engine is not taking it for some reason. Semper Fi!
 

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Could somebody have left a rag in the intake somewhere?
 

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No, it would cause restriction in air flow or turning of the turbo and no boost. I have seen people leaved a rag in the turbo mouth or the intake horn or plenum,

The electrical issues have to be computers, wires or plugs. Do the self test on the dash pod.
You said before you had the ECM tested? Are you sure that was sthe ECM not the PCM.

You definitely should contact ACS, a vendor her.
 

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Oh, forgot to mention, I have no resistance value at all between terminal 6 and 14.
semper fi brother!

which terminal 6x14? ecm?
 

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Yes , what do those two circuits do. Is there a bad ground?
 

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He's talking about the ODB connector (The data link connector (DLC)).
Rectangle Line Font Audio equipment Electronic instrument
Rectangle Font Slope Parallel Pattern

EDIT:
ISO 9141-2 K-line.

Let me explain this one thing that most people don't know about the 1994 - 2002 Chrysler odb.

Now PIN 7 (SCI TRANSMIT) isn't just SCI it's actually special ISO 9141-2 K-line circuit combined with the SCI Tx line.
ISO-K-line allows two-way communication on a single line for generic scan tool.
Data is transferred at a fixed baud rate of 10.4K bps.
Scan tool biases the circuit to 12 volts.
The data is transferred when the 12-volt bias is pulled low.

K-line Initialization.
ISO 9141-2 K-line knows a 5 baud initialization sequence. The Scan tool must start this init by transmitting byte 0x33 to the verhicle at 5 bits per second.
The total transmit time for transmitting byte 0x33 takes about 2 seconds.
After this initialization it is expected to continue communicating at 10k4 baud.

CHRYSLER DRB III Diagnostic Scanner use this most of the time.
SCI - Serial Communication Interface.
SCI consists of:
– Dedicated point-to-point, dual-wire, nonmultiplexed serial communication interface
– Supports both diagnostics and flash reprogramming capability
– Supports multiple baud rates to accommodate
both the low-speed diagnostic command mode (at 7812.5 bps) and the high-speed parameter
interrogation command mode (at 62,500K bps).
The scan tool supplies the bias 5v to the module on the Tx circuit
The module pulls the voltage low to transmit data to the scan tool
The module supplies bias 5v on the Rx circuit.
The scan tool pulls the voltage low to send data to the module
Therefore, the component receiving the data supplies the bias 5v.

NOTE:
TX and RX are abbreviations for Transmit and Receive, respectively.
 

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Discussion Starter · #13 ·
He's talking about the ODB connector (The data link connector (DLC)).
View attachment 954705 View attachment 954706
EDIT:
ISO 9141-2 K-line.

Let me explain this one thing that most people don't know about the 1994 - 2002 Chrysler odb.

Now PIN 7 (SCI TRANSMIT) isn't just SCI it's actually special ISO 9141-2 K-line circuit combined with the SCI Tx line.
ISO-K-line allows two-way communication on a single line for generic scan tool.
Data is transferred at a fixed baud rate of 10.4K bps.
Scan tool biases the circuit to 12 volts.
The data is transferred when the 12-volt bias is pulled low.

K-line Initialization.
ISO 9141-2 K-line knows a 5 baud initialization sequence. The Scan tool must start this init by transmitting byte 0x33 to the verhicle at 5 bits per second.
The total transmit time for transmitting byte 0x33 takes about 2 seconds.
After this initialization it is expected to continue communicating at 10k4 baud.

CHRYSLER DRB III Diagnostic Scanner use this most of the time.
SCI - Serial Communication Interface.
SCI consists of:
– Dedicated point-to-point, dual-wire, nonmultiplexed serial communication interface
– Supports both diagnostics and flash reprogramming capability
– Supports multiple baud rates to accommodate
both the low-speed diagnostic command mode (at 7812.5 bps) and the high-speed parameter
interrogation command mode (at 62,500K bps).
The scan tool supplies the bias 5v to the module on the Tx circuit
The module pulls the voltage low to transmit data to the scan tool
The module supplies bias 5v on the Rx circuit.
The scan tool pulls the voltage low to send data to the module
Therefore, the component receiving the data supplies the bias 5v.

NOTE:
TX and RX are abbreviations for Transmit and Receive, respectively.
He's talking about the ODB connector (The data link connector (DLC)).
View attachment 954705 View attachment 954706
EDIT:
ISO 9141-2 K-line.

Let me explain this one thing that most people don't know about the 1994 - 2002 Chrysler odb.

Now PIN 7 (SCI TRANSMIT) isn't just SCI it's actually special ISO 9141-2 K-line circuit combined with the SCI Tx line.
ISO-K-line allows two-way communication on a single line for generic scan tool.
Data is transferred at a fixed baud rate of 10.4K bps.
Scan tool biases the circuit to 12 volts.
The data is transferred when the 12-volt bias is pulled low.

K-line Initialization.
ISO 9141-2 K-line knows a 5 baud initialization sequence. The Scan tool must start this init by transmitting byte 0x33 to the verhicle at 5 bits per second.
The total transmit time for transmitting byte 0x33 takes about 2 seconds.
After this initialization it is expected to continue communicating at 10k4 baud.

CHRYSLER DRB III Diagnostic Scanner use this most of the time.
SCI - Serial Communication Interface.
SCI consists of:
– Dedicated point-to-point, dual-wire, nonmultiplexed serial communication interface
– Supports both diagnostics and flash reprogramming capability
– Supports multiple baud rates to accommodate
both the low-speed diagnostic command mode (at 7812.5 bps) and the high-speed parameter
interrogation command mode (at 62,500K bps).
The scan tool supplies the bias 5v to the module on the Tx circuit
The module pulls the voltage low to transmit data to the scan tool
The module supplies bias 5v on the Rx circuit.
The scan tool pulls the voltage low to send data to the module
Therefore, the component receiving the data supplies the bias 5v.

NOTE:
TX and RX are abbreviations for Transmit and Receive, respectively.
Had to finish a couple of jobs that actually made money. gonna get back on this tomorrow. Thanks to all who replied.
 

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Had to finish a couple of jobs that actually made money.
I'm pretty much in the same boat all the time ;)
 
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