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Reading Codes 

How to Properly Read Codes

If you have a late model year 2000 – 2002 Dodge truck you can read the codes by turning the ignition switch to the “run” position from the “off” position 3 times within 5 seconds and leave it in the “run” position and stare at the odometer.

 

To help your diagnosis, write down the information displayed, so you don’t forget. To be sure the codes read are pertinent to the current issue, we recommend that you clear the codes after you read them, to see if they come back when the problem reappears. Since some scanners, as well as disconnecting both batteries for half an hour trick, do not dependably clear all the codes, we suggest that you reread the codes before starting the engine to be sure they are actually cleared.

 

Then drive the truck until the problem reappears, and then reread the codes. If there is no new code, that is very valuable information, and if you do have a newly set code, it is most likely relevant to your symptom. If you have a 1998 - 99 or a grumpy 2000, reading codes this way will not work, so you’ll have to read the codes with any OBD II compatible scan tool. Most auto parts stores will do this for free for you.

Pertinent Codes 

  • 216 Code

    • In our experience the 216 code is NOT a “Death Code” as some people say. It only tells you the Injection Pump can’t attain full timing advance to provide good fuel mileage and power. If this is the only code and you don’t have any drivability issues, the VP44 does not need to be replaced, and most likely will not put you on the side of the road. If you do have the 216 code you should check your Lift Pump pressure under load as lift pump pressure is what moves the timing piston and advances timing, so if Lift Pump pressure is low, that may be the cause of the 216 code. If the pressure is good, then the code means the housing of the Injection Pump is worn out, which all by itself, still isn’t a good enough reason to replace it, in my mind.

    • If the engine won’t start, and you haven't opened nay fuel lines or replaced the fuel filter since it last ran, and you have either or both a 1688 or 1689 code, the truck will never start until you replace the injection pump, 99% of the time.

    • If you want to be 100% sure of your diagnosis, follow the No Start diagnosis below. These codes indicate either a serious internal mechanical failure, such as a seized rotor, or that the computer on the top of the Injection Pump is not communicating with the ECM, thereby turning on the high pressure fuel to the injectors. Other circumstances like stray RF (radio interference) can set these codes and therefore confuse or misdirect an accurate diagnosis, so this is where symptoms have more merit than just codes, when diagnosing this fuel system.

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  • Code 1693

    • ​This code means there is at least one code in the other computer, the PCM, which has nothing to do with the fuel system or fuel system drivability problems. Sometimes an automatic transmission can cause a drivability issue and appear to be a fuel system issue. In this case codes in the ECM and the PCM should be noted, and combined with the drivability symptoms and a phone call to us, we can help you differentiate and diagnose the problem. To come up with an accurate diagnosis of this fuel system sometimes, you have to prove all the other components that could cause your problem are indeed good, and therefore not the cause of your problem. After you have done that, you have no choice but to condemn the Injection Pump.

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  • Code 123​

    • Rare and usually indicate an ECM problem​.

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  • Code 234​

    • Generally ​means the MAP signal voltage is too high.

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  • Code 237

    • ​Code 237 means the MAP signal voltage is too low.

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  • Codes 251 & 253

    • These codes mean the fuel solenoid is not working correctly and when associated with a drivability issue is a very compelling reason to replace the VP44.

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  • Code 1688

    • This is the only real code that means "game over" for VP44​. This, coupled with a 251 or 252 or 253 code means, don't waste your time, a replacement pump is needed.

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  • Code 1690 or 336

    • Indicates a signal issue with the Crankshaft Position Sensor, and when associated with a drivability problem, necessitates replacement.

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