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Ask Amedee Your Own Question
Amedee
Amedee, Dodge Technician
Category: Dodge
Satisfied Customers: 24399
Experience:  ASE certified tech advanced level specialist. Wisconsin certified emissions state inspector
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No bus no gas gauge reading wont start bought new pcm still

Customer Question

no bus no gas gauge reading wont start bought new pcm still no start was driving and it just shut off as though its not getting fuel the security light flashes and no bus on odometer
Submitted: 1 year ago.
Category: Dodge
Expert:  Amedee replied 1 year ago.

Hello and welcome! My name is ***** ***** I can assist you with your question. Can I start by getting your VIN?

Customer: replied 1 year ago.
1b7hl48n72s6122852
Customer: replied 1 year ago.
waitingfor answer
Expert:  Amedee replied 1 year ago.

Thank you for the VIN! Does the check engine light come on with the key on? Does the throttle position sensor have 5 volts going to it with the key on?

Customer: replied 1 year ago.
it does
Customer: replied 1 year ago.
I checked there is 5 volts to it
Customer: replied 1 year ago.
i answered your question waiting for response
Expert:  Amedee replied 1 year ago.

Hello and sorry for the delay! I had to step out and my phone was not working to reply back. Anyway, do you know if the ASD relay is activing when cranking the engine over?

Expert:  Amedee replied 1 year ago.

Still waiting for your reply.

Customer: replied 1 year ago.
how do I check asd relay
Customer: replied 1 year ago.
I triede a new pcm do I need to have it flashed if I ordered the exact on . it did not change anything . there is not 5 volts at the tps sensor with the key on unplugged I get 1.5 volts with the sensor plugged in and piercing the wires I get 0 volts
Expert:  Amedee replied 1 year ago.

Hello and sorry for the delay! Did you check the powers and grounds going into the PCM before replacing it? If so, what pins did you check and what were the results?

Customer: replied 1 year ago.
what pins do I check on the pcm for power
Customer: replied 1 year ago.
what does it mean if I have no 5 volts to the tpms bur I do have 5 volts to the cam sensor and there is no spark to the plugs
Expert:  Amedee replied 1 year ago.

Hello!

If there is no voltage at the TPS with the key on, then the computer is not awake. Does the check engine light come on with the key on for a bulb check?

Customer: replied 1 year ago.
the check engine light only comes on when the no bus message appears c1 number 2 and 22 where at 12.2 volts key on and 31 and 32 were ground no voltage
Expert:  Amedee replied 1 year ago.

Please send over the VIN number again as it says invalid VIN

Customer: replied 1 year ago.
back probing 5 volt supply only getting on 3 volts im unplugging sensors till I get 5 volts so far nothing any ideas
Expert:  Amedee replied 1 year ago.

Please send over the VIN number again as it says invalid VIN

Customer: replied 1 year ago.
im getting 5 volts backprobing both 5 volt pcm wires
Customer: replied 1 year ago.
1b7hl48n72s612852
Customer: replied 1 year ago.
waiting for response I don't have computer at home and waiting for a response im running out of time at work sorry if I sound frustrated give me some ideas or possible fixes
Expert:  Amedee replied 1 year ago.

Hello and sorry for the delay! Next, check the 5 volt power supplies for shorts to ground. The Manifold Absolute Pressure sensor, Throttle Position Sensor, Crankshaft Position sensor, Camshaft Position sensor and the A/C pressure transducer are all powered by the two 5 volt supplies coming from pin 17 on the C1 connector and pin 31 of the C2 connector.

Expert:  Amedee replied 1 year ago.

You could cut this wire a few inches from the PCM to see if the reference voltage comes back. This way you will know if there is a shorted sensor or wiring issue shorting out the PCM.

Customer: replied 1 year ago.
BOTH PINS HAVE POWER AND I ALSO CHECKED THE GROUND TERMINALS IF I ORDER A PCM DO I NEED IT TO BE FLASHED IN ORDER TO WORK .
Expert:  Amedee replied 1 year ago.

YES, I do believe so

Customer: replied 1 year ago.
DOES IT SOUND AS THOUGH THE PCM IS THE PROBLEM
Expert:  Amedee replied 1 year ago.

YES, it does. As long as the PCM is not getting shorted out when this happens and the powers and grounds check out good when this happens, then yes, the PCM is bad and will need to be replaced.

Expert:  Amedee replied 1 year ago.

I am glad I can help! Please dont forget to honor your good faith deposit by rating my answer as "excellent service" for assisting you with your question.

Customer: replied 1 year ago.
we where driving and the vehicle just shut off we checked for power and ground on the pins you mentioned everything was good when we went to start the vehicle the gas gauge did not register but everything else lit up and the mi. indicator went to no bus im ordering a reman. pcm and sending it to get flashed have I done all I should do .
Customer: replied 1 year ago.
you stated yes it sounds like the pcm as long as the pcm is not getting shorted out when what happens there is good ground and good power at the pins doesn't this mean its getting all the pcm needs to operate
Expert:  Amedee replied 1 year ago.

Hello! YES, if the PCM is good and all the inputs are good, the PCM should operate. If not, it is bad and needs to be replaced.

Expert:  Amedee replied 1 year ago.

Hello! It's Amedee from just answer. I am just checking in to see how things are going and to see if you need any further assistance? Let me know!

Customer: replied 1 year ago.
had the pcm replaced and i had it flashed now imgetting a misfire the vehicle ran good for 2days but it was as though the truck was 100% now im wondering whats up no bus or engine codes thats wierd
Expert:  Amedee replied 1 year ago.

Hello! Your saying that the PCM was replaced and now the engine starts and runs? The No bus message is there?

Customer: replied 1 year ago.
but after a day of driving now it has a bad misfire it just happened allof a sudden any suggestionns
Expert:  Amedee replied 1 year ago.

So at least we got it running right? Excellent! I am glad I was able to help get it running!

Customer: replied 1 year ago.
BUT IT ONLY RAN FOR A DAY NOW IT MISSES SO BAD ITS NOT DRIVABLE AND NIS CALLING FOR A PO202 AND 90351 WHATS THE NEXT STEP
Expert:  Amedee replied 1 year ago.

The next step is to find out which cylinder is misfiring and then check for spark, fuel and compression on that cylinder.

Customer: replied 1 year ago.
GETTING FUEL AND SPARK HAS COMPRESSION
Expert:  Amedee replied 1 year ago.

HOW DID YOU CHECK FOR THESE AND WHAT WERE THE RESULTS/READINGS?

Customer: replied 1 year ago.
i did compression test and fuel pressure test they are all good but now the vehicle is not starting like before it has a no bus and it only turns over .what should i test next . after ireplaced the pcm thevehocle ran great for a day then it starting missing as though the pcm was messing up the timing giving me thecodes i told you p0202 90351 then it went to no bus and would not start . was it a bad pcm or is there something electrical. the onlyconfussing part is it did rungood for a day
Expert:  Amedee replied 1 year ago.

So the engine cranks and does not start? What is the fuel pressure readings? What is the engine compression readings?

Customer: replied 1 year ago.
the fuel could the pressure reading actully show no bus i thought thaft only came with a no communication pcm
Expert:  Amedee replied 1 year ago.

Thats correct.

Customer: replied 1 year ago.
ok i only checked the fuel rail for fuel i also pulled the plug and thevcylinder blew out with what appeared to be compression but if theres a fuel related problem then why did it rungood after the replacement and flashing of thecomputer does a bad cylinder cause no bus and if so the old pcm was good or did it go in limp mode
Expert:  Amedee replied 1 year ago.

IT sure sounds to me like it is an electrical issue. However, I need to understand the big picture in order to point you in the right direction.

Expert:  Amedee replied 1 year ago.

Hello! It's Amedee from just answer. I am just checking in to see if you need any further assistance?