How do you know if a car is lying to you? - Transmission Digest

How do you know if a car is lying to you?

Sometimes a vehicle comes into the shop with a code in memory and a concern, and it is quick and easy to follow the code and find the source of the problem. But how do you know if a car is lying to you, trying to throw you off the trail with some false information? This is a question we must ask ourselves quite often in the automotive industry. The following is an example of a dishonest vehicle and how we went about catching it in its lie.

The vehicle in this story is a 2014 Dodge Ram C/V Tradesman. The van is equipped with a 3.6L V-6 engine and a 62TE transmission. This vehicle came to us after the owner had another shop install a used transmission, and upon installation it was found to be setting a code and going into limp mode. Apparently, this was the second attempt at a used transmission without success, so the customer decided to bring it to us to see if we could figure out what was going on.

Since there had been previous work done on the van, we took some extra time, looking over things like wiring, connectors, grounds and just the general quality of the installation. There were no obvious issues found with the installation process.

After our visual inspection and a fluid level and condition check, we performed an alternator and battery test. These also checked out. The next step involved hooking up the scan tool and checking for codes. This yielded both engine and transmission codes. The engine codes were P0405 (EGR Position Sensor), and P0420 (Catalyst Efficiency).

The transmission side had code P1745 (Transmission Line Pressure Too High) for too long. Upon seeing this code, while monitoring PIDs I looked at the desired vs. actual line pressure, and there was a difference between the two. I wondered if the previous shop had possibly overlooked or was just unaware of the procedure to reset the variable line pressure (VLP) counters and then doing a quick learn on the transmission. I figured it wouldn’t hurt to give it a shot.

Upon trying to perform the reset, the scan tool would not complete the procedure and instead gave an error message that the conditions were not correct. I tried it once more with the same results. What was preventing it from performing the reset? I was using our Snap-On Zeus to perform this task and have done so many times with no issues. Since I was having an issue in this case, I decided to connect the WiTech instead, and see if I had a different result. Unfortunately, I did not; I still got the same error that the conditions were not correct. There are not many conditions that need to be met in KOEO. Really all the tool says is, “The engine must not be running to perform this function.” (See Figure 1).

RRTech-FIG-1-1400
Figure 1.

I did double check that the calibration was up to date using the PDF file you can download from the Chrysler Tech Authority site. It was.

I started looking at the data while the van was running, going through all the PIDs when I noticed something missing: There was no turbine speed RPM while the engine was running, and the vehicle was in park. Interesting. There was no code for input speed sensor signal, so I had not specifically looked at that PID in the beginning. I wondered how this could play into the error I was getting, but it didn’t make sense that it could affect the procedure in KOEO since no signal is generated under that state. I went under the hood and looked at the connection to the input speed sensor. It is easy to get to as it is located on the top of the transmission. (See Figure 2).

RRtech-FIG-2-600x600
Figure 2.

The connector looked good, so I decided to pull the sensor out and inspect it. There was quite a bit of metal on it. (See Figure 3).

RRTech-FIG-3-1400
Figure 3.

At this point I had the service writer contact the customer and get permission to order a new turbine speed sensor. The customer agreed and the sensor was ordered. Once it arrived, I installed it into the transmission, cleared the codes and started the van. I once again attempted to reset the VLP, and it reset it right away without issue. I brought up the desired and actual line pressure PIDs, and now the values correlated with each other as they should. The van was now out of limp mode, so I decided to take it for a road test. It operated flawlessly. In the end, the vehicle didn’t tell the truth about was going on (no turbine signal codes) but was instead setting a code relating to line pressure sensor.

I later found out that when the used transmissions were installed in the van by the previous shop, the sensors were transferred over from one transmission to the next, so the failed sensor just kept getting moved over to the next unit. This was the cause of the same code and symptom across the different transmissions. Since the sensor itself was not setting a code, it kept getting overlooked as they were looking for a line pressure problem per the code.

In the end a simple fix had cost a shop a lot of time and money because the vehicle was not telling the truth about the source of its problem. Not everything is as it seems. Keep interrogating those vehicles!

You May Also Like

Dealing with the increasingly common pin-fit problem

I want to talk a little bit about a common diagnostic misstep or overlooked problem that is prevalent in the automotive repair industry and seems to be on the rise. Pin-fit or tension can deal us a fit sometimes (pun intended), especially if we do not have the proper tools to determine if this mode

RR-Tech-September-FIG-1-1400

I want to talk a little bit about a common diagnostic misstep or overlooked problem that is prevalent in the automotive repair industry and seems to be on the rise. Pin-fit or tension can deal us a fit sometimes (pun intended), especially if we do not have the proper tools to determine if this mode of failure might be the cause. I have a couple of case studies to share that I have seen recently, and will share some testing protocols that I have used over the years to attempt to correctly diagnose a related issue or a code. 

Watch: Replacing a transmission and components

Dave Hritsko and the team have already removed a full transmission in a previous video. This time, see an in-depth explanation of the parts, components, and steps in how they make the upgrade with a remanufactured transmission along with new aftermarket components with the help of students from Ohio Technical College. Related Articles – AMN

Removing-a-Transmission-with-Dave-from-Transtar-1400
Watch: How to remove a transmission

Watch Dave Hritsko from Transtar and team members from Ohio Technical College as they remove an old transmission and replace it with a newly remanufactured transmission. Related Articles – Watch: CVT modules and programming – Watch: CVT fluid diagnostics – Watch: CVT electric and communication codes

Back to square one: When a transmission replacement doesn’t fix the problem

The subject of this article is a 2002 Ford Ranger with a 3.0L V6 engine and 5R44E transmission. There were 191,622 miles on the vehicle when it arrived at our shop. The owner said that the transmission was not shifting correctly and the OD lamp was flashing. Related Articles – Shift of the shaft: Diagnosing

RRfeature-1400
The technician’s duty to the customer

I want to talk about some of the recent trends of particular cars and trucks that we see showing up at repair shops for work to be done. It seems to be a perfect storm of high used car prices, lack of new car inventory, and a bit of economic uncertainty that brings us to

rr-feature-1400

Other Posts

Shift Pointers: Focused DTCs

On occasions when a vehicle’s computer system detects an error, it can set an array of diagnostic trouble codes. The variety and quantity of them require the ability to diagnose diagnostic codes, so it’s nice when codes set that point directly to the problem.  Related Articles – Diagnosing Ford 10R60, 10R80 and 10R140 series speed sensor

Watch: Transmission trouble codes

If you are seeing trouble codes with your transmission, it is important to understand the differences and what each separate code indicates. Watch the video above from Transtar for the details. Related Articles – Road to AAPEX Ep. 8: Paving the way for automotive innovation – Road to AAPEX Ep. 7: Connecting to future automotive

Transmission-Trouble-Codes-1400
Freudenberg-NOK adds new line of TransTec bonded pistons

Freudenberg-NOK has announced a new line of TransTec bonded pistons. According to the company, Freudenberg-NOK bonded pistons are engineered and manufactured by the same machinery and same people as FN pistons, and are made in New Hampshire. Transmission models covered include the ZF 8HP45 and 8HP70, the Chrysler 62TE and the GM 6L80/90. Related Articles

TransTec-Bonded_Pistons-1400
Diagnostic tips for the Ford 6F35

We have all experienced repairs that seem to “go down the rabbit hole,” as we call it. Our subject today is one such issue: a Ford 6F35 transmission with codes P073D or P177F after repair and a complaint of trying to go into Reverse while in Neutral, or a bind in Forward when cold. This

Tasc-Tips-June-Figure-3---6F35-OE-Clutches-1400