Transmission Help!! '02 Elantra

[mcgovern61]

:help: :help: :help: :help: :help: :help: :help: :help:

Hey guys, my youngest daughter was heading off to school this afternoon and our '02 Hyundai Elantra stopped after she backed out of the driveway. The transmission would not go into forward at all and clunked real hard going into reverse. I shut down the engine to take a quick look around, started up and checked the fluid level (normal) and it went into Drive but is stuck in 2nd gear. It still clunks REAL LOUD going into reverse. At the same time, the check engine light popped on.
:fiddle:

Quick research seems to point to the input and output sensors, (which I will buy and change myself on Friday) but I am open to any opinions out there if anyone has had this experience. The car only has 154K miles on it! :shock:

 

[brianinpa]

The only help I can offer is to say you better break out the check book!

 

[AApple]

Gerry, it would be best to have that thing scanned for codes before you start throwing parts at it. From your description, it is in "failsafe" mode, due to one or more codes being set. There's so many things that could cause it that you could wind up throwing a lot of parts and $$$ on it with no results. Get the code(s), and go from there. Most Autozone parts houses(and some others too) will scan it for free, and give you a printout(if you ask for it).
A bad speed sensor will not keep it from moving forward, but any code that activates the failsafe mode WILL cause a harsh reverse on those. :wave:

 

[joedrum]

sheesh what worthless junk tech ....all are force to deal with now days ...in my opinion

 

[mcgovern61]

AApple » Fri Sep 18, 2015 12:03 pm[/url]":1v2mjpx3]
Gerry, it would be best to have that thing scanned for codes before you start throwing parts at it. From your description, it is in "failsafe" mode, due to one or more codes being set. There's so many things that could cause it that you could wind up throwing a lot of parts and $$$ on it with no results. Get the code(s), and go from there. Most Autozone parts houses(and some others too) will scan it for free, and give you a printout(if you ask for it).
A bad speed sensor will not keep it from moving forward, but any code that activates the failsafe mode WILL cause a harsh reverse on those. :wave:

Thanks Joel! The code is for the transmission range sensor (P0705) and the second code is basically the check engine light was signaled from the transmission ECM. The TRS is available online, but I need the car running before the AM so it looks like a trip to the Hyundai parts dept. ($48 in stock)
:thanks:

 

[mcgovern61]

joedrum » Fri Sep 18, 2015 12:11 pm[/url]":1idbtlmf]
sheesh what worthless junk tech ....all are force to deal with now days ...in my opinion

Understood Joe, except this feature is a transmission fail-safe made. It holds the car in 2nd gear so that you can get it home (or to a shop)! Not a bad feature and hopefully may have prevented any other damage?

 

[zman]

How did we ever get by without technology in cars , well the plastic,thin metal and sensor industry is booming.

 

[AApple]

So it also had a P0700 code on the engine side, eh?
The MLPS("range sensor") could possibly keep it from having forward. Or, it's also possible the sensor kept the shifter from moving into Drive completely. Hopefully, the MLPS will take care of the problem, and she'll be go to go with the car. After installing it, be sure to put a few miles on it, and have it re-scanned before turning her loose on a long road trip. k:

 

[mcgovern61]

You guys are gonna love this.........what does a broken tail light have to do with a transmission failure???? :fishin: :nea: opcorn:

 

[slabghost]

Not a thing on any of my cars!

 

[mcgovern61]

Here goes..........

Yesterday when the car failed to go into drive and stayed in neutral, another issue had arisen that I figure was secondary to the problem; the turn signals stopped working. BUT, the 4 way flasher did work and they share the same flasher unit so I knew the bulbs were OK and figured it might be a fuse or the control arm.

Fast forward to today.....research on the web showed that going into fail safe mode for an '02 Elantra was apparently not uncommon and the most common culprit is the input and output speed sensors. (Not the only culprit, just most common.) I found it interesting that the trans even had a fail safe mode! :music:

While researching the issue I also looked up the turn signal problem with no luck at all. Most of the information always assumed both signal and flasher were out and replace the flasher unit or the push button. Head to Advance Auto since they were the only local store that had the input and output sensors in stock and they would check the engine codes for me. They check the codes, but only give the number and will not tell you what they are!! (Liability in case they give out the code as a diagnosis, you buy the parts and it doesn't fix the problem, they are on the hook apparently.)

Look up the codes and it points to the transmission range sensor (the device that reads where the gear shift is in relation to the trans itself). Pull the sensor to check and it is original, but appears to be working mechanically (maybe not electrically). Lined it up and did several test found in the Hyundai sites....no dice. :head bang:

 

[mcgovern61]

So, I take a break and decide that while the battery is disconnected to look into the turn signal issue. One site wants to check the fuse, but I could not find a diagram with the fuses labeled in the car, the manual or the Haynes book!! Finally, I find a schematic online for the fuse panel and locate the turn signal fuse. Funny thing is, that fuse also powers the backup lights. (Hmmmmm....)

Pop a new 10 amp fuse in it and the turn signals come back on! :yahoo:

Start the car and go into reverse and the car clunks real bad and the turn signals go off again! Check and the fuse is blown again. :headscratch:

Soooooo, now I have to figure out what the relationship could possibly be with putting the trans in reverse and blowing the turn signal fuse. I head over to Hyundai and pick up the TRS unit. The car is still stuck in fail safe mode (only go 45-50 MPH and stuck in 3rd gear now). I decide that while there, I would change the fuse on the turn signal one more time. Voila, they work again. I avoid going into reverse and drive back home. Pulling out of the parking lot at Hyundai, I realize the car is in first gear??? :shock: :roll:

Driving home, it is shifting smoothly in all gears????? I am stumped now?? How does changing the turn signal fuse fix the transmission??? :fiddle: :swoon:

 

[mcgovern61]

I get back home and sit down (wisely) and decide to diagnose this issue and process a little deeper before installing any parts.

> Go into reverse.......fuse blows, transmission goes into fail safe, turn signals stop working.
> Replace fuse.....turn signals work (if the car is going forward) and the transmission shifts smoothly.


Blown fuse.......dead short......easy, but where and how can the relationship be made????? Well, when the car goes into reverse, the back up lights come on. The backup lights operate on the same fuse as the turn signals. The transmission range sensor detects the location of the gear shift as well as the position of the shifter in the transmission and sends a signal to the transmission ECM, which in turn monitors the input and output speed sensors, which in turn controls when the automatic transmission shifts gears.

Low and behold, the power circuit for the TRS (and the back up lights) comes from the same fuse as the turn signals. Blow the fuse and the TRS has no idea what gear position the shifter is in and the ECM automatically defaults to transmission fail safe! :builder:

So, what is blowing the fuse? A walk around the car reveals a tiny little hole in the right rear brake/turn signal lense. Follow it down and the whole bottom half of the lense is full of water!! :swoon:

Pop the unit out and find the turn signal and backup lights are also down in the bilge full of water!! (Was my car sinking at some point?) :hihihi:

Dump the water out, dry out the lense and bulb sockets, install the new TRS and just for yucks installed a new input speed sensor since I already bought it and the symptoms I had on the highway in the past not always going into overdrive seemed related. Reset the ECM and start the car.. VOILA, it runs perfect and shifts smoothly AND the turn signals work!! arty:

I'll tell ya, I was a little scared on this one.....I though for sure the trans took a big dump and we were looking at replacing the car! :moped:

 

[mjanderson]

Wow! Glad it wasn't something worse or more expensive.

 

[dan filipi]

Good to know, check for blown fuses first.
Glad you got it sorted out Gerry!

 

[AApple]

Not surprising at all. Without looking at a wiring diagram, I'd bet that same fuse also powers the TCM.
I found(on one of my Trans tech databases) another instance of the MLPS causing a no go forward from a few years ago. Different car, but same type trans.

Date: Fri Oct 15 13:04:09 PDT 2010
Subject: F4A51, No forward in D4 after overhaul. Sets code P0705
Vehicle: 2001 Chrysler Sebring
Posted Fix: Replaced the Park/Neutral switch

Problem / Fix: This vehicle had a very delayed engagement into drive in D4 if it engaged at all, and it set a P0705 Park Neutral Switch DTC. If you dropped it into D3, or any other drive range, it would engage right away. The shift cable was adjusted properly.

The park/neutral switch passed the resistance tests for all ranges but we still supected it was the culprit so we installed one off a stock unit and that fixed the problem.

I find it strange that the park/neutral switch would cause no drive in D4, so I thought I would post it.

Tod Chretien - TRNW Inc.

Glad ya got it taken care of, anyway. :good: :clapping:

 

[Steve83]

Nicely done! I wonder how many vehicles end up in the junkyard because of something simple causing something major, without any real damage done...

 

[Ansimp]

I would love to know if your old TCM is still good Gerry. This is not the first time that I have heard of a blow fuse or faulty bulb creating other issues with ECM or BCM.

 

[jpwinger]

Here's one for the books. 1999 ford ranger 4.0 engine. Overdrive switch didn't work I though switch on gearshift selector was bad. I got a used one 25.00. While taking panels off to get access to wiring I though I would check switch one last time before pulling wires through column. Switch worked just fine. I had been on ranger forms last night and someone said check backup lights to see if they worked. They didn't. Checked fuse and it was bad. Changed fuse then checked overdrive switch it worked just as it should. Seems back up lights and overdrive switch shared same fuse. And all was well. And now I have a spare gearshift selector. Well it could have been much worst. Jerry.

 

[mcgovern61]

Ansimp » Sat Sep 19, 2015 2:13 am[/url]":8ecwl9aq]
I would love to know if your old TCM is still good Gerry. This is not the first time that I have heard of a blow fuse or faulty bulb creating other issues with ECM or BCM.

I would question that too, EXCEPT, the transmission is running smoother than ever (I think because I changed out the input speed sensor). I just came back from DMV for the vehicle inspection and emissions inspection and the car passed everything! :yahoo:

I am real pleased I was able to get this car fixed with minimal cost for parts and it is running a lot better. Time will tell if the ECM will hold up I suppose. But I would be under the opinion that it either works or it doesn't work and right now it is working! :yes: :thanks: