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Hello everyone,

I am a retired elevator mechanic and I make a little extra income by "flipping" inexpensive used cars and trucks.
In this case, I found a beautiful (225K miles) 2001 Durango 4x4 on Craigslist with an asking price of $1200. The owner purchased it with 170K miles in 2009 and had the engine replaced two years later. Supposedly, the only problem with the truck was a CEL that was diagnosed at a garage as P1733 4c pressure switch circuit fault. The owner was told that it had a bad solenoid in the tranny and quoted a hefty repair price. The decision was then made to sell the truck. That's the story I was told.

After a test drive I used my code reader to confirm the P1733 fault along with P0442 and P0445 evap leaks. I have had pretty good luck with solenoid repairs in the old cars I buy so I was not too concerned about it. The truck was very pretty with a great interior and a very smooth and quiet engine. All the electrical worked perfectly and it was all factory.
The truck would start and drive normally until you stopped or slowed down, then the transmission would go into limp mode and seemed to slip a great deal when you accelerated from a stop.

Anyway, I talked the owner down to $800 and drove the truck home.

I always research any problems that these old vehicles have by checking the relevant online forums. I found that this truck had the 4.7 engine and a 45RFE automatic transmission. To my dismay, I also found that this particular transmission had a solenoid pack that was replaced as a (high dollar) unit and that you could not replace only one bad solenoid. But the salvage yard is my buddy and I dove into the problem.

Visual examination revealed that the fluid was new and the pan was sealed VERY sloppily with red form-a-gasket. I also found that all the engine grounds were left disconnected and one tranny mounting bolt was not tightened down. The front drive shaft was also missing. All this pointed to a very poor quality engine swap in 2009.

I dropped the pan and saw that the two filters were almost new. The pan was clean with no debris at all, but the form-a-gasket was dabbed and smeared all over. I pulled the valve body out and in doing so I was shocked to see that the large connector on the harness had been badly butchered. ALL of the wires had their insulation stripped off, some as much as 1 inch immediately adjacent to the plug. Each wire was laboriously wrapped in a piece of electrical tape that was beginning to slip out of place. This was a fairly large plug with a regular forest of wires and it was located in a very small space between the exhaust pipe and the tranny itself. It would take hours to retape (a very poor solution) and replacing the harness was not an option budget or time wise. I laid on my back and stared up at the mess for a while until I started thinking outside the box.

I went to Lowe's building supply and bought a spray can of liquid electrical tape. I made a series of light coats on the entire section of wires until each strand was thickly insulated from one another and then continued the coats until the entire section was one solid rubber cable. After letting it dry I was pleased to see that I had a very strong and durable repair.

I could find no physical damage to the valve body so I reinstalled it and plugged the harness back in. Then I made use of a real gem that I found while researching the problem with the transmission. The website Daignostics & Troubleshooting Automotive Transmissions, TransTech Diagnostics Sunrise, FL 45/545RFE/68RFE Tests is an amazing resource. There I found step by step electrical diagnostic procedures that only required a VOM, along with beautiful electrical circuit prints. It was a lifesaver and allowed me to thoroughly check all aspects of the solenoid pack, (including the pressure switches) from the TCM harness plug next to the radiator. This was probably the best free resource I have ever come across and it de-mystified the confusing subject of transmission electrical failures. I printed the relevant page and followed the instructions , and when I was done I was assured that there was no problem with the solenoid pack OR my wiring harness repair.

I purchased a filter kit and 5 quarts of ATF+4 and started buttoning up the unit. That is when I found the real problem. There are two filters in these transmissions. There are warnings online that the sump filter has a little collar with an o-ring that must be installed on the tranny BEFORE you put the filter in place. This makes an airtight seal where the neck of the filter inserts into the tranny. You have to pop out the old collar and then seat the new one. The collar is STORED on the filter neck when you open the box and it LOOKS as if you just leave it in place and mount the filter. But the instruction sheet in the box warns against that and tells you the proper method of installing the filter. If you do not do this then the filter is not properly sealed and it will suck air and cause the fluid to foam.

The person who installed the old filter had not done this. In fact, not only had he left the collar on the filter neck, he left the old collar in place on the tranny also. The unit was sucking air and causing the fluid to foam. This was the reason that there was a pressure loss and it would go into limp mode when it was time to downshift! Mystery solved!

That left the emissions faults to deal with. Low and behold, the fuel tank purge line runs right next to the transmission. The line was not secured to the floor pan and was allowed to rest on the exhaust pipe just aft of the exhaust manifold. It being a plastic/vinyl line, it melted in two. The system could not get a good vacuum on the fuel tank during its test checks and thus threw a large and small leak CEL code.

To make a VERY long story short, The truck started and drove with no CEL and no pending codes shown on my reader. The tranny shift points are undergoing the learning procedure and are smoothing out nicely.

Poor mechanical service created what appeared to be a very expensive transmission failure and came lose to causing the truck to be scrapped because it was not worth the expense of a transmission rebuild or replacement. The dealership and repair shops suggested that the tranny was fried and attempted to sell the owner a new unit.

That is what happens when you take a failure code at its face value. Sometimes the code is a symptom and not a cause.

I outlined my experience here to make the information available to others who might be trying to rescue their truck from a confusing transmission issue that forces the truck into limp mode. Sometimes it is something small that is an easy and inexpensive fix.

Thanks for reading my WOT!
BlackSheepKenny
 

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This is what being a mechanic is about. Congratulations on a great repair and a great write up. Thanks.
 

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Thanks for the excellent write up!

Hello everyone,

I am a retired elevator mechanic and I make a little extra income by "flipping" inexpensive used cars and trucks.
In this case, I found a beautiful (225K miles) 2001 Durango 4x4 on Craigslist with an asking price of $1200. The owner purchased it with 170K miles in 2009 and had the engine replaced two years later. Supposedly, the only problem with the truck was a CEL that was diagnosed at a garage as P1733 4c pressure switch circuit fault. The owner was told that it had a bad solenoid in the tranny and quoted a hefty repair price. The decision was then made to sell the truck. That's the story I was told.

After a test drive I used my code reader to confirm the P1733 fault along with P0442 and P0445 evap leaks. I have had pretty good luck with solenoid repairs in the old cars I buy so I was not too concerned about it. The truck was very pretty with a great interior and a very smooth and quiet engine. All the electrical worked perfectly and it was all factory.
The truck would start and drive normally until you stopped or slowed down, then the transmission would go into limp mode and seemed to slip a great deal when you accelerated from a stop.

Anyway, I talked the owner down to $800 and drove the truck home.

I always research any problems that these old vehicles have by checking the relevant online forums. I found that this truck had the 4.7 engine and a 45RFE automatic transmission. To my dismay, I also found that this particular transmission had a solenoid pack that was replaced as a (high dollar) unit and that you could not replace only one bad solenoid. But the salvage yard is my buddy and I dove into the problem.

Visual examination revealed that the fluid was new and the pan was sealed VERY sloppily with red form-a-gasket. I also found that all the engine grounds were left disconnected and one tranny mounting bolt was not tightened down. The front drive shaft was also missing. All this pointed to a very poor quality engine swap in 2009.

I dropped the pan and saw that the two filters were almost new. The pan was clean with no debris at all, but the form-a-gasket was dabbed and smeared all over. I pulled the valve body out and in doing so I was shocked to see that the large connector on the harness had been badly butchered. ALL of the wires had their insulation stripped off, some as much as 1 inch immediately adjacent to the plug. Each wire was laboriously wrapped in a piece of electrical tape that was beginning to slip out of place. This was a fairly large plug with a regular forest of wires and it was located in a very small space between the exhaust pipe and the tranny itself. It would take hours to retape (a very poor solution) and replacing the harness was not an option budget or time wise. I laid on my back and stared up at the mess for a while until I started thinking outside the box.

I went to Lowe's building supply and bought a spray can of liquid electrical tape. I made a series of light coats on the entire section of wires until each strand was thickly insulated from one another and then continued the coats until the entire section was one solid rubber cable. After letting it dry I was pleased to see that I had a very strong and durable repair.

I could find no physical damage to the valve body so I reinstalled it and plugged the harness back in. Then I made use of a real gem that I found while researching the problem with the transmission. The website Daignostics & Troubleshooting Automotive Transmissions, TransTech Diagnostics Sunrise, FL 45/545RFE/68RFE Tests is an amazing resource. There I found step by step electrical diagnostic procedures that only required a VOM, along with beautiful electrical circuit prints. It was a lifesaver and allowed me to thoroughly check all aspects of the solenoid pack, (including the pressure switches) from the TCM harness plug next to the radiator. This was probably the best free resource I have ever come across and it de-mystified the confusing subject of transmission electrical failures. I printed the relevant page and followed the instructions , and when I was done I was assured that there was no problem with the solenoid pack OR my wiring harness repair.

I purchased a filter kit and 5 quarts of ATF+4 and started buttoning up the unit. That is when I found the real problem. There are two filters in these transmissions. There are warnings online that the sump filter has a little collar with an o-ring that must be installed on the tranny BEFORE you put the filter in place. This makes an airtight seal where the neck of the filter inserts into the tranny. You have to pop out the old collar and then seat the new one. The collar is STORED on the filter neck when you open the box and it LOOKS as if you just leave it in place and mount the filter. But the instruction sheet in the box warns against that and tells you the proper method of installing the filter. If you do not do this then the filter is not properly sealed and it will suck air and cause the fluid to foam.

The person who installed the old filter had not done this. In fact, not only had he left the collar on the filter neck, he left the old collar in place on the tranny also. The unit was sucking air and causing the fluid to foam. This was the reason that there was a pressure loss and it would go into limp mode when it was time to downshift! Mystery solved!

That left the emissions faults to deal with. Low and behold, the fuel tank purge line runs right next to the transmission. The line was not secured to the floor pan and was allowed to rest on the exhaust pipe just aft of the exhaust manifold. It being a plastic/vinyl line, it melted in two. The system could not get a good vacuum on the fuel tank during its test checks and thus threw a large and small leak CEL code.

To make a VERY long story short, The truck started and drove with no CEL and no pending codes shown on my reader. The tranny shift points are undergoing the learning procedure and are smoothing out nicely.

Poor mechanical service created what appeared to be a very expensive transmission failure and came lose to causing the truck to be scrapped because it was not worth the expense of a transmission rebuild or replacement. The dealership and repair shops suggested that the tranny was fried and attempted to sell the owner a new unit.

That is what happens when you take a failure code at its face value. Sometimes the code is a symptom and not a cause.

I outlined my experience here to make the information available to others who might be trying to rescue their truck from a confusing transmission issue that forces the truck into limp mode. Sometimes it is something small that is an easy and inexpensive fix.

Thanks for reading my WOT!
BlackSheepKenny
Outstanding information! I have an 02 Durango with the 4.7 and haven't had any issues with the transmission, but this info could save me or anyone else with the same model some real trouble and money! Nice work!
 
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