Dreaded LX470 cutting out no codes!

Joined
Jul 7, 2020
Messages
15
Location
Australia
Hey all,
Last couple of weeks after no mods or anything my 2005 LX470 has been cutting out while driving. I’ve been trying to establish a pattern of when it happens but the closest I can get to is when I make a turn and/or on a decline, slight one usually. Today it happened in an incline! No signs prior, all I get is cut out, lights in dash reset and sometimes I can save it and drive away and sometimes I have to roll off to the side with no PS and restart it. Anyway I have read a lot from other posts and have initiated a troubleshooting plan so wanted to give back to the community and let you all know how it’s going …..

1. Brand new Genuine MAF - no change
2. Loosened petrol cap (read that somewhere) - no change
3. Moved breather bracket away from fuel resistor to allow airflow around resistor - no change
4.a.Noticed my deep belt is sorta not tracking perfectly, a little slackness in the tensioner so about to install new genuine tensioner assembly
4.b. Had some belt squealing for some weeks and changed out the alternator thinking maybe that caused the cutting out - no change but belt squealing stopped.
4.c. PS pump sounded iffy, so replacing that right now with tensioner and new belt.

That’s as far as I’ve got right now.
Not keen on doing fuel pump yet as I figure if the fuel pump was failing it would splutter and die rather than completely cut off. I think it’s either something electrical, or the belt causes timing to slip… dunno.

Next steps are swap out ECU main relay and Fuel Pump Relay with new genuine which I have already bought.

After that I’m going for fuel pressure regulators and fuel pump.

After that I’ll go back to the drawing board probably dust off the old multimeter and do some needle in the haystack work.

Oh, I’ve also changed my battery terminals on a new battery.

Happy to take any other suggestions or experiences.
 

BullElk

SILVER Star
Joined
Jun 19, 2013
Messages
2,816
Location
Saraland, AL
My experience has been a bad fuel pump will cause it to just die. It will also cause a long crank then maybe start… then not start at all. The first symptoms I have seen is LX just going dead when slowing down and/or on a slight incline.
 
Joined
Jul 7, 2020
Messages
15
Location
Australia
Ok so update is changing the belt, steering pump and tensioner pulley did not work. It may be just me but I feel like the throttle is a bit doughy and so to that end fuel pump will be replaced today. I really hope this fixes the issue as I’m quickly running out of options. Im no good with testing circuits so might start practicing now just in case.
 
Joined
Jul 7, 2020
Messages
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Location
Australia
Ok so fuel pump replaced - no dice and lost a fuel hose clip somewhere in the underbody!!!!
I then decided I may as well swap the fuel filter out, and while I’m there pop in those two new relays (ECU main and Fuel Pump).
Took it for a test drive, no shorter than previous ones and it didn’t cut out. I’ll be taking a longer drive later and I’ll report back.
 
Joined
Jul 7, 2020
Messages
15
Location
Australia
Nope. Same thing again cut out about 10 times in the space of 10 minutes. Not enjoying this.
 
Joined
Aug 7, 2022
Messages
72
Location
Deep Creek, Florida
This might just 'pizz You off', but I'd recommend taking it to a legit. lcl mechanic & have them diagnose? 1-They can see PENDING Codes, 2-they can run live stream on 30 different potential issues at once, and if nothing else, most likely figure out What Your problem is/are, so You can still go fix IT Yourself? Others thought it fuel, I think it electric, You replaced fuel pump & filter so maybe I'm right; Point is, they can diagnose (& yes, w/all the stories of 'it never happens when they're testing it', sort of becomes total BS when You say it crapped out 10x in 10 min.?) Sounds like Your issue is escalating? I don't even know if these 4.7L's have a CPS (Crank or Cam Position Sensors), but what You're describing is exactly what my Dodges do when either of those 1 are starting to fail, and they get Worse, until replaced, then they act like a 'new truck' all over again? & in the case of a Crank Position Sensor, if You let it cool down, it runs like a charm again....until nice and warm, then poof, nothing. I think Your problem is either an electrical relay, or a failing sensor (& I've been wrong as much as right in the past, so take it w/a grain of salt, but trust the dude who rolls over the $10,500. testing cart & plugs it up to Your LX, is worth the $$ when he says, "Computer says You've got a failing 'x & y', but not 'z' "? Then, even if You've gotta call a tow truck to get it back home & swap out Your grief (& for therapy, take those parts out on the back porch w/a baseball bat and pound them in to rubble....You Will Feel Better!), and It was worth the $ to know 'chasing rabbits down holes is no longer Your worry. & I'd Love to know what the final solution turns out to be?
 
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Joined
Jul 7, 2020
Messages
15
Location
Australia
Funny you should mention it as after my last set of changes and tests I thought “this is beyond me now” and I rang in to get it booked. 8 week wait at the best diag place I know, and then called my back up guy and left a message. Not having any codes was bugging me but I figured they’d have some futuristic machine that could find the needle in the haystack. Not being able to let it go, as I waited for my guy to call back I kept pursuing. There was no way it was mechanical it had to be electrical. I turned my focus to the area under the dash driver side, where I had previously tested by pulling out the HUD from the OBD. This appeared to have helped but ultimately didn’t resolve the issue. I then get around and found that the push button start module was loosely sitting on top of the acc pedal, where the APPS wiring is. I thought that’s not right, and moved it into the footwell more and secured it a bit better. I hate that thing. The previous owner installed it and smart key entry module as well. Anyway, turns out that was the issue. Car has now run for 2 days no dramas! It made sense that no codes were being thrown up because there was nothing wrong with the car per se. The module was shorting out or had a loose earth and killed the ignition circuits randomly. The ECU wouldn’t have registered a fault as this is an external item to the car and as far as The ECU was concerned, ignition was being switched off normally.

Thanks to everyone for posting their stuff up on the forums as the suggestions cost me lots of money but helped lead me to the path of the immobiliser, albeit an external one.

My joy is immeasurable, my knowledge of my car has been deepened and my confidence in the car is once again restored.

Cheering!
 
Joined
Jul 7, 2020
Messages
15
Location
Australia
P.s. I now also have a spare GOOD throttle body, PS unit, serp belt, ecu relay, fuel pump relay, fuel pump, fuel filter, battery terminals, fuel cap, MAF and PS air idle valve. 😂
 
Joined
Aug 7, 2022
Messages
72
Location
Deep Creek, Florida
Funny you should mention it as after my last set of changes and tests I thought “this is beyond me now” and I rang in to get it booked. 8 week wait at the best diag place I know, and then called my back up guy and left a message. Not having any codes was bugging me but I figured they’d have some futuristic machine that could find the needle in the haystack. Not being able to let it go, as I waited for my guy to call back I kept pursuing. There was no way it was mechanical it had to be electrical. I turned my focus to the area under the dash driver side, where I had previously tested by pulling out the HUD from the OBD. This appeared to have helped but ultimately didn’t resolve the issue. I then get around and found that the push button start module was loosely sitting on top of the acc pedal, where the APPS wiring is. I thought that’s not right, and moved it into the footwell more and secured it a bit better. I hate that thing. The previous owner installed it and smart key entry module as well. Anyway, turns out that was the issue. Car has now run for 2 days no dramas! It made sense that no codes were being thrown up because there was nothing wrong with the car per se. The module was shorting out or had a loose earth and killed the ignition circuits randomly. The ECU wouldn’t have registered a fault as this is an external item to the car and as far as The ECU was concerned, ignition was being switched off normally.

Thanks to everyone for posting their stuff up on the forums as the suggestions cost me lots of money but helped lead me to the path of the immobiliser, albeit an external one.

My joy is immeasurable, my knowledge of my car has been deepened and my confidence in the car is once again restored.

Cheering!
Glad You WON! Walking sux! My suggestion (unless You're worried about theft), I'd rip that damned Kill (aka 'start') switch the helloutta there? aftermarket crap like that can ruin Your whole day (or week)! Smart key module not so much, but those 'start buttons' when not factory are a constant cause of grief for many owners after installation? To the Victor go the spoils, Good Job on not throwing in the towel! Damn, 8 Weeks? That's crazy. You could get it SHIPPED over here, diagnosed, & shipped back sooner than that! Congratulations, been at wits end like You were before, it's an awful feeling . :bang:
 
Joined
Mar 4, 2012
Messages
719
Location
South OC
Nice work! Persistence paid off. Crazy how some things happen. Take those aftermarket items off if you don’t like them!
 

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