GX470 starts but dies - after timing belt change (1 Viewer)

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Oct 9, 2022
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Location
SE Missouri
2006 GX470...installed new timing belt and water pump. I'm 99% certain belt is correctly installed. But after reinstalling battery, the truck will start but then immediately die. Giving a little throttle does not do anything. Sometimes it will run for 3 seconds...never longer than that. Double checked all my connections and vacuum lines.

Only other thing is that I'm also replacing brake rotors, pads and hoses. So right now, I have two brake hoses disconnected and brake fluid reservoir is very low. But I would not think that would prevent the engine from running.

Truck is new to me...only about 3 weeks. But it has been running perfectly.
 
Yes, it looks good. A mechanic friend said it's likely due to the battery being disconnected for so long (4 days) and that it needs to be "re-programmed".
 
When I’ve disconnected my battery it will sometimes start up, run for a couple seconds then turn off but it has only ever done it once. After it does that, I restart it and it runs normally. I would say you’re possibly missing something if it’s happening over and over again. Maybe check crank and cam sensors as they are easy to misroute the wire and end up with issues
 
I disconnected my '03 Sequoia battery overnight and it was very difficult to start and keep running. It stalled 12-15 times in 10 minutes and I had to power brake it to keep it running, while driving. Finally, I got it to idle very slowly (450 rpm) with my foot off the gas, and I let it idle for 15 min, and it figured itself out and ran fine after that. I can't believe Toyota's base fuel mapping is so lame that the truck won't run....

If yours runs for 3 seconds, I suspect it's something else.
 
Mine usually dies once after disconnecting the battery, then fires back up and runs fine. That should only be happening if your fuel mapping is way off of the base due to something wrong with the vehicle (vacuum leak, exhaust leak, injector problems, sensor problems, etc) or engine modifications (mine probably does it due to a CAI and headers). You could always give it a spray of ether/carb cleaner into the intake/throttle body to see if it keeps running and eventually revises the fuel mapping.

Are you 100% sure the belt is on right? This seems like a problem that could occur if you were a couple of teeth off on the timing belt, which is not that hard to do. I helped a buddy put a belt on his 2UZ Tundra and we almost put it back together wrong as one of the cams had rotated 90 degrees on it's own and we didn't notice it until we triple-checked things before putting the timing cover back on.

Lastly - where are you in SEMO? I'm in Farmington. Not many GX's around here.
 
I'm in Poplar Bluff. Ironically, my brother, who lives in Farmington, is to blame for getting me into this hobby. He has a LX470 and is fixing it up for overlanding. Once I get this going we plan to go on rides together with kids and grandkids.

After installing the timing belt, I rotated the crank 2-3 times to make sure all the timing marks lined up. No problem there.

I got TechStream going and it gave me 4 codes. 3 related to throttle pedal position sensor (P0121, P0123, P2135)...and 1 code for cam position sensor - P1340

I removed the cam cover and double checked all the connections and that I had installed it correctly and everything looks good.
 
Tried a couple things. Then cleared the codes. Shut everything down and restarted Techstream and did a Health Check. No codes. Then tried to start the truck. Same thing...tries to run but won't. Then checked for codes and got the P1340, cam position sensor. So everything points to that being the cause, but I don't see any issue with it or the wiring. Not sure how to test it, so I guess I'll order a new one.
 
Good luck and hope that is the issue!

FYI I occasionally organize rides in the Black River/Clearwater Lake area. PM me if you get your GX going and are ever interested.
 
I am 80% sure it's either cam position or crank position sensor related. There is a notch on each sprocket of camshaft and crankshaft make sure those notches are synchronized. Double check your timing on crank pulley and cam pulley are set to top TDC. Make sure your cam position sensor harness and crank position harness are properly plugged. To test a faulty cam position sensor or crank position sensor, get a multimeter unplug those two cam position sensors and 1 crank position sensor, set the millimeter to ohms, each sensor should have resistance between 950-1250 ohms. If the resistance is higher or lower than the specified value that will indicate faulty sensor. Keep in mind these cam or crank sensor rarely fail but it can fail. The resistance value that I am writing here is from 1UZFE engine and I believe 2UZFE may have similar value. Look for moisture or corrosion in harnesses of cam and crank sensor.
 
Thanks...that's helpful. I did check voltage at the harness side - #3 terminal - and I have 5 volts which is good. Did not check anything yet on the crank sensor since we did not touch it during the timing belt/water pump procedure. I'll check resistance values today.
 

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