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Discussion Starter #1
I’m currently rebuilding a salvage 2019 Hyundai Elantra 2.0L Limited vehicle bought at auction. This vehicle was involved in an accident and as a result the engine was damaged, I replaced the engine with a donor engine from a 2017 Elantra Same mileage and the engine runs beautifully. I refilled all the fluids, when I tried to drive the vehicle transmission Goes into reverse and when shifting into neutral it still goes in reverse and when in drive it doesn’t move almost like it was in neutral. I want to add that I drove this car before the engine swap and shifted in gears just fine, I checked the connections and cable linkage and everything looks right. Any ideas?
 

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When shifting, does the display in the dash cluster show P-R-N-D consistent with the lever position?
Does the car roll in P, or does the park lock work properly in P and not in any other range?
If you move the lever over sideways from D to the manual gate, you will see the dash display change the "1". Does the car go forward in "1"? If not, bump the lever forward and the "1" changes to "2". Does it move in "2"?
 

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Repairables? Practically history with unibody vehicles and if then engine was smashed what about the front suspension? No legal way to repair these then you may have a heck of a time getting insurance with a salvage title. Had buddies work on repairables, working at Macs today. Care to post a photo of what you purchased?

Back in the good old days, huge majority of automotive components were rebuildable, but now practically all components are throwaway. And the largest one is the unibody.

Some guys lost their butts, forgot to price in the cost of air bag, ECU, BCM components.
 

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Discussion Starter #4
When shifting, does the display in the dash cluster show P-R-N-D consistent with the lever position?
Does the car roll in P, or does the park lock work properly in P and not in any other range?
If you move the lever over sideways from D to the manual gate, you will see the dash display change the "1". Does the car go forward in "1"? If not, bump the lever forward and the "1" changes to "2". Does it move in "2"?
When changing gears it does Show in the dash display Reverse, Neutral, Drive and it also goes into 1 and 2 on manual mode. When in Park it does Park lock fine everything shows as it should be it just doesn’t do what it’s supposed to in Neutral and Drive.
 

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When changing gears it does Show in the dash display Reverse, Neutral, Drive and it also goes into 1 and 2 on manual mode. When in Park it does Park lock fine everything shows as it should be it just doesn’t do what it’s supposed to in Neutral and Drive.
To confirm - it moves forward in manual 1 and manual 2? It moves backward in R?
And in N it still moves backward?
It sounds like the shift cable is out of adjustment As long as the car moves forward and backward with no slippage, the converter, pump and hydraulics are ok, and so are the gearsets and clutch packs.
Double check the shift cable...
 

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Discussion Starter #6
It does not move forward at all, not in Drive 1 or 2 When in Drive it acts like it’s in Neutral.
 

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Is this the car's original transmission? Might it have been damaged in the collision?

If the car will back up, the torque converter, oil pump, gearsets and at least two clutches are alive. Change direction to "forward" and one more clutch needs to be good - the "underdrive brake". I doubt it is dead if everything else is alive, so I'm left to wonder why it won't go forward. The shift cable and the transmission range sensor are the two ways to tell the car which direction you want to travel.
This link shows shift cable adjustment - Hyundai Elantra: Adjustment - Shift Lever. Repair procedures - Automatic Transaxle Control System - Automatic Transaxle System - Hyundai Elantra MD 2010-2020 Service manual
 

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Thank you for all your help, I will definitely look at this link and really appreciate the info. I’m left to wonder since I had to remove the original transmission and obviously remove and disconnect the TCM from the harness Would this cause the TCM the need to be re-learned And have It programmed at a dealership?
 

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Thank you for all your help, I will definitely look at this link and really appreciate the info. I’m left to wonder since I had to remove the original transmission and obviously remove and disconnect the TCM from the harness Would this cause the TCM the need to be re-learned And have It programmed at a dealership?
I was under the impression the transmission was original and only the engine changed. If you can get the TCM from the donor car, you can swap it into your car and it should shift normally with no need to reset the adaptives. You'd want to be sure the part numbers are the same between the donor car's TCM and yours. Parts can change from year to year and with various options on different cars.
All Elantra GLS/SE/Limited models with the 1.8 or 2.0 engine use the same transaxle so there won't be any mystery TCMs out there other than the later Elantra Sport 1.6T models that use the 7 speed clutch cookers instead of the legendary 6 speed model we have.
 

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Discussion Starter #10
The transmission and TCM are the original, the only variable is the engine which is out of a different vehicle I swapped the original transmission and installed in the new engine. Would this cause the TCM the need to be reprogrammed?
 

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The transmission and TCM are the original, the only variable is the engine which is out of a different vehicle I swapped the original transmission and installed in the new engine. Would this cause the TCM the need to be reprogrammed?
Original transmission and TCM are a matched set and should work well together. Replacing the engine should not have any effect, and certainly not as serious as "it goes backwards in neutral and won't go forward". You could always diagnose it "Brooklyn" syle: Get someone who doesn't hate you and want you dead to sit behind the wheel with the engine running, disconnect the shift cable from the top of the transaxle, move the lever to "D" to fool the computer into not freaking out when the car moves. Without the cable attached, have the "driver" hold their foot firmly on the brake and you can manually click the little lever on top of the transaxle from P to R. Lift off the brake and see if the car backs up. Brake again. Click again to N and lift off the brake. Car should not move. Click again to D (while not standing in front of the car) and lift off the brake and see if the car goes forward. Then go three clicks back from D to N to R to P.
If it does move forward with no shift cable connected and the shifting done Grand Theft Auto Style by twisting the lever at the transaxle, then the shift cable adjustment is the problem. If it doesn't move forward then you might have an internal (valve body) issue.
 

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So refreshing to see helpful posts from someone who really knows what they are talking about.
 

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Discussion Starter #13
DMLEXPERT Wanted to ask you something else that might or might not be related to this trans issue. When installing the engine I lost the tape identifying my heater hose connections (cheap blue tape) and trans cooler since they’re all in about the same location. I have enclosed a picture of this hose connections and maybe you can give me a second look just to make sure they’re correctly connected where they’re supposed to. The bottom hose is from the trans cooler And connects to the bottom of the engine block, the middle one comes from the upper radiator hose/coolant inlet and connects to the inlet of the heater hose and the furthest to the right, the heater outlet goes to the other side of the trans cooler Thank you again.
 

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I believe the cooler lines connect on the driver side - the upper back cover of the transaxle, and they're two curved steel tubes that are joined together by a sort of strap. I'm not sure which is "out" and which is "return" but they're not the same size or type as the heater hoses. The trans cooler lines carry ATF to and from the radiator side tank. The other hoses connecting to the engine, thermostat housing, and to the firewall for the heater core carry coolant. What you describe sounds like the heater hoses - to the core from the thermostat housing and then the return usually by the water pump. The radiator will have two larger coolant hoses - out and back from the engine - and then two smaller hoses connected to those ATF lines I described.

This is the top view of the transaxle. Front of the car is the bottom of the image, and the cooler lines are the two pipes on the lower right.

 

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Just about the only mechanical thing that shift lever does is put the transmission in park dropping a small pawl in a toothed gear. Oh, it also takes it out of park. Park is also locked by an electric solenoid, to make darn sure you put it in park to switch off engine so your vehicle doesn't roll backwards on your driveway killing your kids. Major lawsuits against the automotive manufacturers mainly because of idiots. One reason why are vehicle prices are skyrocketing.

The big thing the gear shift lever does is rotate a selector switch, what changes what gear you are in is what combination of electrical hydraulic valves are opened or closed that determine what gear you are in, like neutral, no solenoid valves are active, reverse has its own. The signals originate from the engine control computer, use to have its own little box, and if transistors or the microcontroller was bad, around a hundred bucks.

But now all in one box, including cruise control to save on wiring, these boxes are 100% unrepairable and some run around 1,300 bucks. Course if one spark or injector is bad, this same box is trash. But its cheaper to add wires to a connector than to adding a new connector, and OMG, that extra box needs attaching screws.

Had friends and relatives tell me they needed 4,000 bucks for a new transmission, shops don't lie. When the major problem was dirty contacts in the selector switch, use to call this the neutral safety switch, so conductivity only occurs in park or neutral, but now all those extra switches for the transmission gear selection, actually the solenoid valves.

Early AT's had all these controls and brains as part of the transmission, mechanical governors, engine vacuum, and a very expensive control box with mechanically operated valves. All this complicated stuff was eliminated and replaced by a 99 cent microcontroller, but the replacement parts list as skyrocketed.

One nice thing about the Elantra, does have an engine undercover, before this, road salt would splash on the ECU to AT connector and corrode the heck out of it causing no shift problems. Was a heck of a job to clean those. Oh, not really necessary, you need a new AT and ECU. Also have a brake switch to worry about.

This is telling it like it is.
 

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Oh if you did see that little tiny parking pawl linked to the aluminum housing in the AT, when you leave your vehicle, will always use the parking brake. That greatly relieves the stress on that little tiny pawl if someone taps your bumpers.

Beats walking out to your vehicle seeing AT fluid leaking out of it.

If you have real disk calipers, the only way that pad wear is compensated for is working the parking brake.
 

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The part of the Manual the ECU is called the PCMm power-train control module . That Neutral safety switch is called the Transaxle Range Switch that completes the starting circuit in P or N. Details of the Switch are not shown but has four outputs to the PCM, R. P. N,D, also a brake switch circuit, not shown here, then you see 16 wires connected to the transmission, primarily the eight solenoid valves.

These are 12V solenoids that whose 12 volts original from the starting circuit. Just saying, look for electrical problems.


Is that Transaxle Range Switch, 25 bucks at rockauto.com, been able to take these apart for testing an cleaning, but not sure about this one, under the 100K warranty. The one on my 1988 Supra I remember the most, went bad after 12 months, and Toyota would not give me a new one. It was only inches away from the catalytic converter that cooked the contacts. But they were cleanable, I made a shield for it and has been problem free for the last 31 years. But just like the Elantra using electrically energized solenoid valves for clutch engagement, that car wasn't going anywhere.
 
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