2003 Ram 1500 - OBD2 Won't Com but was...Crank No Spark
 

I'm helping/working on a 2003 Ram 1500. It has a stuck motor and the kid did an engine swap (4.7 to 4.7). Block p/n comes back 2003-2004.

The used/replacement engine would turn over but no start.

It was coming back with a bunch of error codes:

• P0113 code is one of many codes that are created by your car's Powertrain Control Module (PCM). ... If your PCM is returning a P0113 error code, it means that your Intake Air Temperature (IAT) sensor is reading at too high of a voltage.
• P0118 is an Engine Coolant Temperature Circuit – High Input malfunction. This code refers to the engine coolant temperature (ECT) sensor. ... The code is also set if the PCM determines that the ECT sensor resistance is out of specification.
• P0522 code means the sensor is indicating too low of an oil pressure value due to faulty sensor, low oil, or sensor circuit.
• P0123 is the generic OBD-II code which indicates that the Engine Control Module (ECM) has seen the TPS circuit A output voltage go above the sensor's expected voltage specification range. TPS is Throttle Pedal Position Sesor or Throttle Position Sensor
• P0032 is defined as HO2S (Heated Oxygen Sensor) Heater Control Circuit High, Bank 1, Sensor 1.
• P0335 is a generic diagnostic trouble code that stands for Crankshaft Position Circuit Malfunction. The code is set when your car's primary computer—also known as the powertrain control module (PCM)”is unable to detect a signal from the crankshaft position sensor.

A common problem looked to be Crank sensor, cam sensor, bad/wirres/grounds and PCM.

When we got the vehicle to my house, the OB2 scanner would connect and talk. A new fuel pump was put in and a new crank sensor was put in. All the fuses/relays work, it has fuel pressure, turns over, but no spark. The cam and crank sensor have 5V on them.

Pulled the PCM offf, Cleaned all the grounds (back of heads to firewall, battery to block, battery to fender, battery to chassis, fusebox ground) and called it a night.

The next day, Put in the cam sensor. Also was going to swap out the PCM. Also plugged in the connectors to some of the sensors that were not plugged in and someone had some how two backwards. At this point, the OBD2 reader would not read. Also the fuel pump was not working. Happened to find the ground by the fusebox we forgot to hook back up after cleaning (distraction f-up). Hooked it back up, fuel pump now working again.

Where we currently stand:

1. Instrument cluster is not reading. We ran the codes (reset / Key on) and cluster says dome light bad, which it is, and PCM/TCM not talking.
2. The OBD2 scanners, tried two different, will not communicate. I have 12V across pin 4 to pin 16, so there is power at the connector.
3. Cams and crank sensor have 5V to them.
4. No O2 sensors are connected - should not matter, right?
5. Radiator is currently not in and sensors not connected.
6. Fuel pump runs and pressure on the rail
7. No spark
8. All fuses good. ASD relay does click.
9. Swapped out PCM for another (came from a 4.7 Durango however) and it would not talk either. Yes, we had battery disconnected when we did this.

Puzzling thing was OBD2 was talking, now it is not.

Any ideas of where to look next?

Given that a number of sensors are reporting high voltages, I would look around and see if a harness got pinched somewhere, and is now feeding 12 volts on the 5 volt circuit. That will also trash communication with the PCM.

Thanks. Was looking for pinched wires yesterday and couldn’t find any.

the cam/crank sensor are 3 prong. Was reading on the connector, unplugged from the sensor, 5v/com which is correct. But also singalong to common was reading 5V. Thought I’d odd, but not connected and unloaded.

others I think were throwing codes because they were not plugged in.

if any other suggestions to check, please let me know.

I won’t be able to look until tonight


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Do you have scan tool where you can monitor ckp and cmp single and RPM in a wavelength form? Diagnosed many issues doing this….the graph wave should be identical with all three, if one drops that’s the fault

I unplugged a few sensors and PCM is talking again. Now time to trouble shoot further

Not that I know of. I'd have to check what they can all do. One is a Bosch (model/pn no idea) and the other is a blue tooth scanner w/ app for phone.

Current status:

• Checked all grounds, connections, etc.
• PCM is now talking
• Had IAT issue code. Plugged in to different IAT and code and that cleared.
• Cranks but does not start
• Existing PCM in.
• New crank sensor and new cam sensor.
• Codes:
  • 65 - Power Relay Open (ABS) - yeah, no relay in, but should not affect starting, correct?
  • P0335 - Crankshaft Position Sensor A Circuit Malfunction
  • P0032 - Heated Oxygen Sensor Heater Control Circuit High Bank 1 Sensor 1 - yeah, no exhaust on currently. Should not need to start, correct?
  • P0038 - Heated Oxygen Sensor Heater Control Circuit High Bank 1 Sensor 2 - yeah, no exhaust on currently. Should not need to start, correct?

The P0335 for Crankshaft position sensor to be is the biggest issue right now. We put a new sensor in and last time I measured 5V at the sensor (com to pwr). I did not check voltage or signal this time. What is the chances it is the reluctor ring? Could the replacement sensor be bad? Maybe bad PCM? Thoughts?

If the PCM doesn't see the engine turning, (crank sensor) it most certainly is not going to start. You have the correct input voltage, and a good ground, next question becomes, is the sensor actually putting out a signal? A scanner that can read live data should show engine RPM, even while cranking. If it stays at zero, then either the sensor is bad, the wire from sensor to pcm is bad, or, the pcm itself is bad. Even better would be an oscilloscope, to see what the waveform looks like.

You could be having a tone ring-ECM mismatch. Take a look at this video and see discussion at 17:55;


The Martinbuilt videos are as good as you can get for the 4.7.

thanks. I do not have an o-scope. I’ll get a better scanner. Q: Any scanner suggestions <$300?

Also, isn't the crank sensor just a digital TTL output? On (5V) / off (0V)? If so, I should be able to put m-meter on output and turn crank to see it change state? I still like the better scanner or o-scope solution better.. I won't be able to look at this until sometime this evening, but will check all the wires to make sure no issues. Also double check the sensor as I think the sensor is for 2002 and not 2003, but likely all the same.