Ok sorry for being away for so long. Life got in the way lol

So I finally got around to checking things out. Since the code was for the Accelerator Sensor, I looked through all the maintenance receipts kept in the glove box. The previous owner replaced the Accelerator Sensor about a year ago according to maintanence records. So I got under the dash to check things out. To my surprise, I found the mechanic had cut the old harness out and ran new wire from the Accelerator Sensor connector to the connector at the ECU and used crimped wire connectors. Wow! Right!? So I cut out all the crimped connections and soldered the wires together and covered with shrink tubing. Pics are below. So now only time will tell if it throws the code again. It happens around every 50-75 miles.

Now back to the tranny. It still does the hard shifting from time to time. I did change the fluid and filter a while back and it still persists. I have read all your posts and thank you for the replies. I will start looking at sensors for the tranny that I can replace without dropping the tranny........yet. I will start with the temperature sensor. The only code I get is P2138. When that code is thrown, the car immediately goes into limp mode. The code says it's for the Accelerator Sensor, but I've had 1 mechanic tell me it can also refer to the transmission sensors.





Even the insulation on some wires were bad. This work is unreal!

 

That last photo clearly shows bare wire. If that sucker was touching anything metal, it could have been grounding out. Nice job on the repair. If you're going to do it, don't half *** it, do it right the first time is my motto.

 

sad.

Keep us updated

 

Hey Beater, good job rooting out that wiring issue! Solder and heat shrink is the best repair possible! You never want to add resistance to any circuit that is monitored by the PCM, ECU or any type of module, you're just asking for problems down the road! Is there any way that you can pull up a wiring schematic and find out exactly what that exposed wire was, I'm sure it went from the APPS (accelerator pedal position sensor) to the PCM, (power-train control module) but what is it exactly...supply voltage, reference voltage, return signal, etc? It is quite possible that the short, if shorted to ground, may have damaged the PCM or APPS. On drive-by-wire systems (no accelerator cable) any codes in that system will cause fail safe / Limp-Mode operation. If the only code you have now is P2138, I would focus on that first. It very well could be a transmission issue, but if the code is for a APPS malfunction, that code will put the trans. in Limp Mode as a result, not necessarily because the trans is at fault. The transmission has to know what you're doing with the accelerator, so it knows when to up and down shift. Without that signal, it doesn't have enough information or feedback to know what to do. I will try to look into that code when I have time, we are quite busy at work now, so it may take a day or two. In the meantime, try to find out what that wire went to. I know all the wires appear to be the same color, but if you can pull up a connector view of the wiring harness in an on-line shop manual or Mitchell, you can find out the pin location, and what it does. It is also quite possible, with all the wires being the same color, there may be something cross wired. I would also check all the wires from the APPS back to the PCM and make sure they all go to the correct pin locations. Please let us know what you find, and we'll go from there. I think you're very close to getting this issue nailed down!

 

Yes all the messed up wires were for the APPS. One by one I cut out the crimped connectors and used good solder and shrink tubes them. I've gone 50 miles tonight and still no P2138 code which is good, but it has gone up to 75 miles before being thrown.

The trans is still doing the hard shifts. But as usual, I pull over, shut car off, then restart and it is fine again. This has to be a sensor, at least, but no code is thrown for any trans sensor. Could it be the Automatic Trans Control Module?

 

YES!!!!!
That is what I was thinking of!
Still need to drop the tranny to swap it though.

 

But isn't that located inside the center console?

 

Hey Beater, to answer your question, I highly doubt it is a PCM issue. I worked for Aamco Trans for 5 years, and Certified Transmission for 10 years as a Diagnostician. There is no trans control module on your make and model. Everything concerning the eng. and trans is controlled by the PCM. The PCM is not inside the trans, it's either under the hood, or under the dash, maybe center console? All the solenoids and pressure sensors are inside the trans side cover by the inner fender. The Trans will have to be removed in order to access any of these solenoids, temp sensor, pressure switch assembly, or valve body. There is no room to remove the side cover with the trans in the vehicle. The input and output speed sensors are external.

Please read my reply again on 4-29, so as not to repeat myself. A simple code reader my not pick up trans codes, you will need a scanner to access trans data and codes.

Again, if the trans starts shifting hard, then shifts okay for a while after cycling the ignition key, then the PCM is commanding high line pressure...period. Now the question becomes why? If the PCM is seeing a slip, based on eng. RPM, input and output speed sensors, it should set a slip code. If a solenoid is malfunctioning, it should set a circuit failure code, unless a solenoid is mechanically malfunctioning, then it will set a slip code for that too. If the PCM is receiving erratic or wrong information from a sensor, that too could cause the PCM to boost line pressure causing hard shifts, until the next drive cycle. I have seen bad eng. temperature sensors cause this, or stuck open thermostats, where the PCM thinks or sees the engine is still too cold to operate in closed loop, and will drag out the shifts in order to get the eng. up to operating temperature. I have also seen bad Intake Air Temp sensors do the same thing. But, cycling the key won't change sensor data, but it will clear stored transmission cell-tap data with a new drive cycle, causing the trans. to shift normally again, until it sees a problem. Without a scanner, you have no idea what the PCM is seeing...as far as sensor data is concerned.

I really don't believe the PCM is the issue here, either the trans has a slip, a bad solenoid like a pressure solenoid or shift solenoid, or it is receiving erratic or wrong data from a speed sensor, APPS sensor, or some other sensor effecting the trans. Without being able to see scanner data for the transmission, there is no way to properly diagnosis the exact cause of the harsh shifting.

I would recommend taking your Ion to a reputable transmission shop, and spending the $100.00 to have it properly diagnosed. I can't see throwing parts at something, and hopping that fixes it. I also can't see spending 2 or 3K for a rebuilt 4T45E trans, when it could just be a faulty output speed sensor, for instance.

Sorry I can't be of more help, but there is only so much we can do here without getting our hands on the vehicle. Best I can do is tell you how the trans and PCM work together, the logic used by the PCM to control the operation of the trans, and possible causes for the harsh shifting. If I had to guess, I would say something inside the transmission is slipping, and the PCM is boosting line pressure to stop the slip, usually when shifting between gears. If the engine RPM noticeably increases between shifting points, you have a ship, (called a flare) in the world or trans. technicians.

A few more questions: Why did you change the transmission fluid? Was it because of this problem, or did this just start after you changed the fluid? What color was the fluid before you changed it? Did it give off a smell like candles burning, or burnt toast? With 150,000 miles, do you know if the trans fluid had ever been changed before? If this started after the fluid change, what kind of fluid did you put back in...Dextron 6, or something else? What are you checking codes with, a code reader or scanner?

#13: Pressure Sensor Assembly
#305's: Shift Solenoids
#335: Torque Converter Clutch Solenoid
#312: EPC, Electronic Pressure Control Solenoid
#46: Input Speed sensor
#62: Output Speed Sensor

 

Alpha,

There does appear to be a Transmission Control Module on the Ion automatics.
It's 24226863 for the 2.2L in the 2005 Ion 2 and it is separate from the PCM.

That being said, I do not doubt a single thing you stated with respect to what is likely happening within the transmission, or if it is a result of bogus info from that Accel pedal sensor or something else. You have 15 years hands on experience as a diagnostician and have prob seen pretty much everything imaginable.

However, I think the TCM is in this case being fed all the necessary data from the PCM to do the same decisionmaking that the PCM would do -- or possibly the tranny sensors are connected directly to the TCM thus freeing up the PCU for other tasks.

And I'm happy as hell we have a 15 year auto tranny diag expert among us.

I know your head must be getting big, but please understand that the knowledge you share with us in 15 minutes might take 2 months to sort out on our own. And you explain it with just the right amount of detail (for me, anyway).

 

Alpha

Wow! Thank you very much for the in depth response. I'm like a sponge and love to learn stuff. I definitely learned a few things from your post. At this point I truly hope it is nothing inside the trans lol.

Doing some research, I do in fact have the 4T45-E Trans. What I was referring to in the center console is the TCU(had to look it up). I do understand it is hard to diagnose problems without the right tools, but I do appreciate all the insight I can get.

So some good news. I have gone 110 miles without the P2138 code being thrown nor the trans shifting hard. So it's either a fluke, or the repair I did is working. And the hard shifting was do to misinformation from the APPS due to the bad wiring. But I think it is still too early to celebrate. If it does throw the code again, I will pony up the money and head off to a dealership to run a full diagnostic.

To answer your questions: I changed the trans oil thinking the hard shifts were happening due to dirty, bad oil. When I drained it, the oil looked to be done. It was brown, and like you said, smelled like burnt candles. There was no record of it ever being changed. I had receipts for oil changes, but nothing on the trans. I replaced what I drained with recommended Dextron VI and replaced the filter. I used a code reader. Not a full scanner.