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We have a 1996 ch613 Mack that has had the motor change out…

Hello we have a 1996...
Hello we have a 1996 ch613 Mack that has had the motor change out it now has a 1993 model motor. They both had the EM7 V-MAC II Mack motor. It ran good for close to a year then it started missing then it stop accelerating. Does have a check engine light code 84-3 which is VSS the MPH it is Vehicle speed sensor voltage high. I have figured out the miss it has number 1 cylinder has a dead hole. The customer wants to drive it that way he does not think that it has a bad hole. When I crake the line it does not change and it is pumping fuel. I took the nozzle out swat it with 3 and the problem stayed with 1 I then closed valves put air in to cylinder you could hear it blowing in the engine would not hold over 10PSI. The problem is I can not figure out the code. I have check voltage at sensor I have 4.99 Volts at the speedo I have my 5V and my 12V and ground. I check the resistance it was a little low so I replaced the sensor still have the code. Its does this setting still not moving. I have ck all the wiring from sensor to VECU ECM and Speedo all with in specs. Here is the motor inf 1993 E7-350 11GBA 24266P2 3U0573 Then has S430. Need help Any thoughts
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Answered in 27 minutes by:
10/29/2019
Technician: Jeremy, Certified Truck/Bus Technician replied 2 years ago
Jeremy
Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 4,370
Experience: ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, Network Engineer specializing in CAN faults, Aftertertreatment, and vehicle communications
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My name is ***** ***** thank you for using Just Answer. I will assist you with your question today. Please follow-up as needed until we get this resolved.

If you are having engine issues with a low engine threshold, it will throw that fault code on the VSS. I don't know why it will do that, but I have seen that happen before. There is even a note in the tech documents about it.

I have a troubleshooting chart to help diagnose that issue. I will attach it to a link in here so you can go through it. I just went through one this last week for the same fault on a 95. Mine was a bad VECU. If you are getting good voltage, no bad ohms readings, then the VECU will be the culprit. Take a look at the troubleshooter to confirm the proper ohm reading for the sensor part number.

>>>CLICK HERE<<<

Vehicle Speed Sensor (VSS) - Voltage HighP

Fault: 4-1

PID: 84

FMI: 3

Circuit Description:

The Vehicle Speed (MPH) Sensor (VSS) is an inductive sensor. When the vehicle is moving, the transmission output shaft speedometer gear teeth rotate past the VSS tip and a pulsed signal voltage is generated. The Vehicle Electronic Control Unit monitors the frequency of the signal generated by the VSS, to calculate the vehicle speed. The air gap between the sensor and the toothed gear influences the VSS signal output and should be checked if erratic or inaccurate speedometer readings are reported.

Location:

The Vehicle Speed (MPH) Sensor (VSS) is located in the rear of transmission, near the output shaft.

Additional Symptoms:

The reduced power option may be enabled.

Normal VSS Parameters:

Transmission - Resistance at 75° F (23.9° C):

1. OEM T200/T300 - Series with Sensor #64MT413M: - 252 to 308 ohms

2. OEM T200/T300 - Series with Sensor #64MT435M: - 238 to 292 ohms

3. OEM T200/T300 - Series with Sensor #64MT424M: - 146 to 180 ohms

4. OEM T200/T300-Series - with Sensor #64MT439M: - 146 to 180 ohms

5. Allison HD: - 270 to 330 ohms

6. Allison HT: - 2900 to 3400 ohms

NOTE: Diagnostic code 4-1 may be logged if the Engine Load Threshold is set too low in the Vehicle Parameters area of the Vehicle Electronic Control Unit (VECU).

_____________________________________________________________________________

I'm an independent user of the site, like yourself, not an employee. Please consider that I don't know your skill level as well as I can't see, touch, smell, hear the vehicle/machine in question. Please provide as much detail as possible and I will provide as much back. If there is something I have written or a document that I provided that is not understanding to you, please let me know so it can be clarified further.

Ratings and tips are appreciated.

Thank you for allowing me to assist you through Just Answer!

Jeremy

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Customer reply replied 2 years ago
that is the same information that I have. The problem with that is when they change motors they change trans to it has a Eaton fuller trans in it now. I told them the miss in the motor could cause it to do that but they don't think so. I really believe that is what is causing the issue. I told that are the VECU cause I have ck every thing else 3 are 4 times.
Technician: Jeremy, Certified Truck/Bus Technician replied 2 years ago

The Eaton trans should have a similar signal off the VECU.

I am thinking you have a VECU issue since you have a good ohm reading, you have continuity, you have your volt feeds, signal and ground return. That leaves the VECU or a low engine threshold. That is all that is left based on what you have already sated you have completed.

Jeremy
Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 4,370
Experience: ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, Network Engineer specializing in CAN faults, Aftertertreatment, and vehicle communications
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