Hi guys. I have a 2002 TJ Magna 3.5L with 120k on the clock. Its my wifes.

For a couple of months the car had been running rough on idle and stalling randomly. I figured it needed a service as it had been a while and so about 14 weeks ago we had a major service done on the car. Nothing else was done with that major service except brakes and such ($1000). It was identified that during that service we need to change the plugs, drive belts, timing belt and rocker cover gasket (rear was leaking).

The car then sat idle for 12 weeks as my wife wasn’t able to drive (had a baby) and we just used my car for everything.

When I went to start after the 12 weeks it ran ok. Took it up and down the street with no issues. Then the next time I started it the gears wouldn’t change and it went into “limp” mode (flashing N light) and was stuck in 3rd gear and idled roughly.

I pulled out all of the fuses and checked them and then restarted it and it changed gears as per normal but still idled rough.

Last week I had the plugs (all of them), drive belts, rocker cover gasket and timing belt replaced ($970). When I went to pick it up it still ran rough and was back in Limp mode again. They pulled off two sensors, sprayed CRC into them and compressed air and it was then fine but still ran rough. They told me to bring it back the next day as they would clean out the “idle motor?” and they turned the idle up. This has no effect and stalled at the first set of lights when I left.

When I rang them about it they said they had two sensors throwing errors (mass airflow? and barometric pressure?) but that disconnecting those sensors didn’t stall the engine and it should. They deducted that it was probably the ECU and it was $640 to replace (part cost only) and couldn’t guarantee that this would fix the problem.

I then took it to a friend of a friend (the second person to look at the car) who had a look and found nothing obvious ($0) and gave me the number of a diagnostic person.

He came around a few days ago (the third person to look at the car - $145) and plugged in his device only to find no power at the diagnostic pin so couldn't do anything. He did show that the plug leads were loose and two were arcing out on the engine.

I had a mobile mechanic (the fourth person to look at the car - $347) actually change the leads.

Now the car is still in limp mode, the dash indicates a reset each time you start it (flashing 'S', etc) and the central locking doesn't work.

I guess my question is does anyone want to buy it? Just kidding. My wife loves the car and wants it fixed but were running out of options.

The diagnostic guy says to take it to an auto sparky, get the diagnostic pin fixed, call him back to diagnose the issue, then take it to someone to fix that issue which is another 3 trades before even sorting the gearbox.

Is there a one stop shop or a Magna guru I can take it to that can do everything instead of taking it on a tour of Perth?

One fix which is probably a definite would be the fuses in the yellow box in the engine bay, that will sort the door locking and trip computer constantly resetting.

Not sure on the other but it may be the idle stepper motor/controller responsible for constant stalling, that's a bit iffy, as you have a limp mode error, and these may be related or not..

But you can definately lift the yellow square guard around the fuses and replace the blown ones, until some one with more experience chimes in with more help.

Classic heater core leaking issue. I see it often even from dealers who give up and send cars to me.

Check the ecu area, is classic symptom and when you state can not get power to diagnostic plug pretty much seals the deal

Ok the ECU fuse was blown. So it runs and idles now. Will get under the dash and check the heater core later so i know its not a recurring issue.

Tranny is still in limp mode. Since all this started at the same time is it stupid to assume they are related? Is there anything electrical that I can check or do I have to send it in? TransmissionTech in Wangara has been recommended. Anyone heard of them?

Maybe the old disconnect the battery for a while trick.

Check ecu first as ecu and TCU are in same box and heater may be cause of blown fuse

Maybe the old disconnect the battery for a while trick.

Disconnected the battery for about 24 hours before reconnecting today and the tcu didn't reset the error code.



Check ecu first as ecu and TCU are in same box and heater may be cause of blown fuse

Sounds like its worth a look. The car is 45 min from home so can't just popout for a look. Might head up again tomorrow.

Cheers for all the info fellas. Its taken me a bunch of weeks and some dollars but am seeing light on the horizon.

When I had it at AutoMasters before and I went to pick it up, it was in limp mode. The guy put a computer on it and it brought up two sensor errors. He's disconnected those sensors and sprayed them with crc and said it was probably du to,water getting in during the engine clean. When I starts it back up it was no longer in limp mode.

Was this because he had fixed the issue or because he had reset the error using the computer?

When I had it at AutoMasters before and I went to pick it up, it was in limp mode. The guy put a computer on it and it brought up two sensor errors. He's disconnected those sensors and sprayed them with crc and said it was probably du to,water getting in during the engine clean. When I starts it back up it was no longer in limp mode.

Was this because he had fixed the issue or because he had reset the error using the computer?

Smart mechanic, probably fixed the problem, but only time will tell.

Two sensors on top of the gearbox, one reads the input shaft revolutions and the other the output shaft revs. If the TCU (in the ECU) finds discrepencies in the readings, it will put the box in limp mode.
You don't want water in the sensors, keep the hose well away from the top of the gearbox, or cover it up with plastic, a garbage bag will do.

If the limp mode comes back, read the error codes yourself (covered in another thread) and replace whichever sensor throws an error code. They are easy to reach, another sensor can be picked up from a wreckers or Mitsu dealer.

Really, cover the box with a garbage bag, suppose when ever it rains you do this to stop water spray off the road as well

The plugs are sealed, we wash on average 4 or more engine bays each week, never an issue.

If both sensors are reading sus then is not the sensors or the plugs but most likely an electrical issue such as ecu being wet, the chances of both plugs having the seal missing is very remote

hi guys

i had issues closely related to this last night. I'm not too sure if my gearbox went into limp mode as the lights on my Dash (P,R,N,D,1,2,3) weren't lit up and i had no speedo. But it wouldn't change gears. It would go into Reverse and Drive, with a large shunt. The fuse in the cabin for the ECU was blown. I replaced and it was all good. It went into all the gears nicely. But when i drove it this morning, once i selected Drive. POP!! there goes the fuse and back to square 1.

i checked for coolant from the heater inside the cabin and it was bone dry. Well i think it was the ECU.... anyway, i couldn't smell coolant, and nothing was damp/wet.

My car is at Ultratune and i don't want them to charge me Ultra- dollars. So i'm trying to get to the problem before they fix it.

hi there,

I have a verada 3.5 1997 (170ks) on a similar issues to Fatti.

I am not very sure what limp mode means but probably mine is.

When I drive from standstill position I have put extra on the accelerator to get it going (guess it never engaged on 1st gear) probably starts on 2 or 3 gears.

And when I shift to reverse, the car took about 0.5-1 secs to respond and it shunt before engaging in 'R'.

And whenever in 'D' mode the 'N' lights is flashing as well.

Any advice on this?

Had a mechanic to test drive the car he reckon it might be TCU sensors playing up and advice me to send it to Bailey Automatic.

He did say worst case scenario the gearbox is buggered.

Any advice on this? Thanks

hi there,

I have a verada 3.5 1997 (170ks) on a similar issues to Fatti.

I am not very sure what limp mode means but probably mine is.

When I drive from standstill position I have put extra on the accelerator to get it going (guess it never engaged on 1st gear) probably starts on 2 or 3 gears.

And when I shift to reverse, the car took about 0.5-1 secs to respond and it shunt before engaging in 'R'.

And whenever in 'D' mode the 'N' lights is flashing as well.

Any advice on this?

Had a mechanic to test drive the car he reckon it might be TCU sensors playing up and advice me to send it to Bailey Automatic.

He did say worst case scenario the gearbox is buggered.

Any advice on this? Thanks

That's limp mode alright.

Gearbox is probably not buggered. It is more likely to be an ECU issue or a speed sensor. Best bet is to get it to an Automatic transmission specialist to get it checked out.

Flashing neutral light means it's in limp mode.

Research how to read the error codes. It will tell you what is wrong. Probably one of the two speed sensors on the gearbox has a bad connection or is buggered.

hi there thanks for the advice given... i live in perth , belmont and wanneroo area
any recommendation on which transmission specialist that i should bring the car to?
and any estimated cost if its the speed sensor or electrical that is buggered?
do not want to be taken for a ride and ripped off...

thanks

Hi got the car fixed up so i think its appropriate to share given the helps and advices that i have gotten from the forum...

brought the car to Wanneroo Automatic Transmission for free inspection and told me the speed sensor needs replacing... quoted $475.00

thought i would check with other shops just to make sure i am not being ripped off...

got the car to Automatics Transmission R US in geddes road to diagnosed...

been told it would cost $95.00 to diagnosed. they staff there seems pretty honest and one of the mechanics named Drew explained quite a bit to me...

so decided to have a go... called me next morning the input speed sensor is buggered and been quoted 220$ to supply and fit...

gave the go ahead and got the car late in the afternoon and it drives GREAT now...

btw i just cant believe to have the same thing replaced , one cost 475 another cost 220 plus gst... unbelieveable

anyway thanks guys for all the info...

cheers

mine does the exact same thing, but i don't get any codes. As it blows the fuse that powers up the dash.
I don't even have to start the car, i can put the transmission into drive and turn on the ignition without starting and it blows.

last time it fixed itself... well i did move a couple of connectors and the problem went.

do you know which sensor you changed?

Clearly says "INPUT" sensor was changed.
There are 2 sensors on top of the gearbox. Input shaft and output shaft. The TCU in the ECU uses them to calculate how to shift.

With a little bit of research, you can actually identify a gearbox sensor fault yourself, and get a spare from the wreckers. May just be a poor connection at the sensor or water from washing the engine though.

sorry i did read that... got too many things running through my mind trying to work it out.

Input sensor... is that the one with about 10 wires going to it? it's located right underneath the battery. The connector looks identical to the inhibitor switch but it's grey. 6 pins on top row, 4 pins on lower row.
I tried looking it up on the schemetic diagram and the only thing that resembles that plug is the A/T control relay. But that only has 8 wires going to it.


I did some tests on the car, and it doesn't blow the fuse if i disconnect that grey plug. But the D and N do not light up on the dash. P and R do light up.


Maybe i'm reading it wrong.