Wednesday, July 11, 2012

Idles Fine but RPM jumps in drive mode?

2004 Dodge ram will idle fine but RPM jumps in drive mode.

Also it feels like truck pulling forward when coming to stop.

WHY THIS PROBLEM IS NOTICED?


This issue is already been noticed many as times at our repair garage.As per your problem described this is caused by the torque converter clutch staying locked up when you are stopped.
In the front of the converter there is a disc clutch that is turned on at certain times to give a mechanical lock between the engine and trans.


BUT WHY IT FEELS LIKE TRUCK IS GETTING PULL FORWARD WHEN STOPPED?

First of all i will say your dodge cummins engine is very powerful engine as compared to other vehicle model engine.

On most of engines a locked up converter clutch will cause the engine to die when you come to a stop, but the Cummins has enough power that it will stay running,Even though converter clutch is locked.

EXACTLY WHY THESE HAPPENS?

As per vehicles electrical working procedure when you come to a stop.The ECM(engine control module) sees the increased engine load and just ramps up fuel and boost to keep the engine running.
And that is what makes you feels like truck is pulling when you are trying to stop.

But with this same condition if you shift the shifter up into park or neutral it quickly relieves a huge load on the engine, and this cause RPM surge issues.
That  is why you may have noticed the RPM's jump up a bit before settling down to normal.


OK,I UNDERSTOOD THE THEORY OF THE PROBLEM.BUT WHAT PART IS EXACTLY FAULTY?

The problem which you mentioned is caused due to faulty/worn out sticking valve in the valve body, bad converter clutch solenoid, leaking seals on the trans input shaft, or the converter itself.
As per details you dodge truck model uses 48RE transmission.
As per our garage vehicle repair experience Usually on most of  48RE trans this same types of problems are  caused by a failed converter.


SO SHOULD I REPLACE THE CONVERTER OR DO SOME TROUBLESHOOTING?

First confirm the problem.other then converter issue,i have also mentioned some other possibilities.
The problem like sticking valve in the valve body, bad converter clutch solenoid, leaking seals on the trans input shaft.
So start inspecting and checking this possibilities too.

FROM WHERE TO EXACTLY START TROUBLESHOOTING?


First remove the valve body and make sure there are no valves hanging up. If ok then  replace the solenoid pack at that time since the valve body has to be removed to do it and it's already apart, and at that point the problem would either be the solenoid or converter. Since the solenoid pack is cheaper and easier I suggest  replace it then and hope that takes care of it, but if not then you know the converter and input shaft seals will need to be replaced.As that's the only possibility left.

OK,WHERE IS THE SOLENOID LOCATED?

The solenoid which you need to replace is converter clutch solenoid.There is also one more solenoid located there,its called Governor solenoid.You don't have to replace governor solenoid,but the converter clutch solenoid.


The governor solenoid and transducer are used together with the ECM to control governor pressure, governor pressure controls upshift and downshift timing.But governor solenoid is not the issue in your case.

You have to replace the replace the double solenoid on the silver bracket on the right side of the valve body, above the governor solenoid and transducer.



The converter clutch solenoid is located on the right side of the valve body above the governor. It's a double solenoid mounted on a single silver bracket as mentioned earlier.The solenoid comes with the trans internal wiring harness. This is the solenoid that can cause the problem you are noticing.

WHAT IF REPLACING THE SOLENOID IS NOT HELPING?


First i suggest to  replace the converter clutch/overdrive solenoid .Its the second one on the bracket is overdrive.That should take care of the problem.But if that doesn't take care of it then you know the converter itself is the problem and will need to be replaced. Because Solenoid is cheaper option and converter is costlier one.I suggest replacing the solenoid first and confirm the issue.


WHATS THE PART NUMBER OF SOLENOID AND CONVERTER.AND WHAT IS THE COST OF PARTS?

As per part service manual.It states



Part number for converter clutch/overdrive solenoid is 52118500AB.
&
Part number for converter is R2118868AC.

And for the cost the solenoid pack runs about $120 and torque converter runs about $400.


This details will help.
Thanks.

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