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Robert R
Robert R, ASE Certified Master
Category: Dodge
Satisfied Customers: 3932
Experience:  Dodge Master Certified, Dodge Sprinter Certified
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Here is what I got. I have a 1999 Dodge Ram 2500 24v l6

Customer Question

here is what I got.
I have a 1999 Dodge Ram 2500 24v l6 Cummins turbo diesel w/ 260,000 miles. For the past year the truck has been parked due to a major issue that I cannot figure out. A year ago when I was driving home the truck began to surge and then went into limp mode (was not generating any boost psi). After about 10 sec the issue resolved itself and began to generate boost again. This happened 3 or 4 more times over 2 months then one day it went into limp mode again and did not recover.
The last time it did this it sent a code which is po237 (turbo boost sensor A circuit low) and p1698 (voltage control circuit malfunction). I replaced the boost sensor but that did not fix the issue and I replaced the ecm and that got rid of the p1698 but still did not fix the limp mode issue.
I have replace the exhaust manifold due to some small cracks, I replaced the turbo, both batteries, and alternator. I removed an edge ez tuner I had installed for fear that this was the issue. My fuel pressure gauge fluctuates between 5psi and 20 psi but usually stays around 15psi. The stock lift pump was removed years ago and replaced with a fass 150 pressure pump. I am at a loss on this one, any help you can provide is greatly appreciated.
Submitted: 9 months ago.
Category: Dodge
Expert:  Robert R replied 9 months ago.

Hello, welcome and thanks for asking your question. My name is*****'m a Certified Auto Technician with 28+ years experience. I will do my best to assist you. please keep in mind that I may need to ask questions of you before I can answer. When you reply please feel free to add as much detailed information as possible pertaining to your concern.

has it been scanned again since then? What codes are present now?

Customer: replied 9 months ago.
Thank you.The only code it is showing now is po237. I scanned it after I installed the new ecm and po237 popped back up. This has been about a month now and I start it once a week to keep the batteries charged up and this is the only code it has produced.
Expert:  Robert R replied 9 months ago.

At this time since you already replaced the MAP sensor (Boost Sensor) and the ECM then I suspect a wiring problem. At this time you need to check the wiring for problems and repair as necessary.

Here is a wiring diagram and a diagnostic flow chart. With this info you should be able to use a multimeter to check the wiring and the flow chart should be able to help you through the procedure. Just follow the diagnostic procedure as best as possible without the use of the factory scanner (DRBIII).

Wiring Diagram ----> Click to view

Diagnostic procedure -----> Click to view

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

Customer: replied 9 months ago.
Thank you,I will check it first thing tomorrow and get back to you.
Expert:  Robert R replied 9 months ago.

Sounds good, I'll be here in case you need any additional info....

Thank you,

Robert

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Customer: replied 9 months ago.
I checked the wiring with out a drb. Al lthe specs came back in the proper range.
Customer: replied 9 months ago.
one more thing I noticed. After I checked the wiring I decided to clear the code to see what happens. I let it run for a good 45 min and the code did not pop up during this time. I also reved it up for a while and still it was clear. I decided to take it out and after 5 min of driving the same code set again. It seems to happen only when under load.
Expert:  Robert R replied 9 months ago.

I'm still leaning towards a wiring issue. I've seen intermittent wiring issues cause the needless replacement of sensors and ECM's. At this time I would recommend to run a new signal and sensor ground wire to the MAP sensor and see if that helps...

Keep me posted...

Thank you,

Robert

Customer: replied 9 months ago.
Will do
Expert:  Robert R replied 9 months ago.

You might also check the 5 volt supply wire for a full 5.0 volts at the MAP sensor with the sensor disconnected. If it is less than 5 volts, you may check this wire for a short to ground...

Keep me posted...

Thank you,

Robert

Customer: replied 9 months ago.
I will be getting to running a new wire on saturday. I did check the 5 volt supply and that is good.
Expert:  Robert R replied 9 months ago.

Sounds good.

Keep me posted and let me know if you have any additional questions...

Thank you,

Robert

______________________________________

If you need additional information, don't hesitate to ask, I am happy to help as long as necessary to help solve your concern. Remember, a "Positive" Rating will not close this question, You can post a reply here whenever you want, even after rating my answer!

Thank you!

  • Robert
Customer: replied 9 months ago.
i finished the rewire and finally got a chance to test it today. The code still pops up when its under load.
Expert:  Robert R replied 9 months ago.

Do you have a mechanical gauge so that you can check actual manifold pressure and compare it to the data from the MAP sensor? This will be the next step so you can verify that the MAP sensor is transmitting correct data.

Keep me posted...

Thank you,

Robert

Customer: replied 9 months ago.
I do not have one on hand but I will order one tonight.
Expert:  Robert R replied 9 months ago.

sounds good, let me know the results and we can go from there...

Thank you,

Robert