grantd57

My 2001 RX300 decided to start overheat when under load (driving) but not while idling. Pulling the coolant temperature switch resulted in car not starting. Jumping the connector (shorting) did not help it start. I replaced the switch and it started right up! However, overheating while driving (but not when idling) remained the same. I decided to go with a flush and tune up. As you probably know, 1, 3, 5, cylinders are a *****! It wasn't enough to get a u-channel bolt removed from the throttle body. It seems the inlet manifold also sported one that could not be reached by normal means. I had to remove engine cowling around windshield which included windshield wipers. Finally got it all out, replaced plus (amazing it was running as bad as they were) and replaced with bosch iridium ones. (I know, I know...I heard comments about Bosch). Regardless after full reassembly of fuel injectors, spark plugs etc... I finally turned the key. Nothing? I checked for spark and nothing.

I plugged in OBDWiz scanner and got DTC's P1300 through 1325, all cylinders!! Along with (for good measure) P0753, 758, & 768! And finally P1760.

This all happened while the car just sat there, getting coolant flushed and spark plug changed. I check all connectors/vacuum hoses and all checks out. No shorts in wiring (that I can find). So is it the ECM just arbitrarily decided to die?

Help!!! It suspicious that all 6 ignition circuits went bad and all at once! A Fuse that powers ECM? Why not all codes?

AnthonyMtz

For 1 take out them bosch plugs ASAP! I suggest you try and clean up the old spark plugs a bit and put those back in and try to start the car could be all bad plugs next is the ignition coils but I doubt all 6 would die at the same time...and go from there, also you mentioned you unhooked the fuel injectors maybe something wasn't plugged in right also if you removed the throttle body you have to make sure you connect all the lines back in the correct order (I screwed up there myself) anyways I also heard about another member that had to replace his coil pack that could be the corporate good luck with the diagnosis.

Wht95scort

The car DID run before YOU messed with it so whatever it is you caused. Having said that, recheck all your connectors. The coils all go through coil number one which is rear of engine next to the pcv. Chances are that plug isn't in all the way or you pulled a wire out. Also make sure you have the ground wire that goes on the back of the intake on. On a side note why did you think a tune-up would fix your overheating issue?

grantd57

Thanks for your replies. I will pull the wire off cyl #1 and check it's circuit to the ECM. Then I will plug into the module pin with a single connector, go through meter (+ to pin - meter - ground) crank engine and see if I get voltage. Would this prove/disprove I have something going to ignitor?
One more thing, I first pulled the coolant temperature switch. Instructions said I could short it out and essentially bypass it. It wouldn't start. I put a new switch in and it started right up! However, It would idle up to normal temperature but immediately overheat under load. This could be anywhere from 25 to 45 mph!
One person I talked with, and I tend to agree, thermostat and water pump failure would result in over heating under idle or load conditions. Right?
I did the tune up as the old plugs were horrible. Not even sure why it ran! I found an old plug laying in the valley from a previous tune up once I got the inlet manifold off.
You said the 'order' I hooked up throttle body with mattered? I didn't try any particular 'order' but am sure all connections were plugged in.