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Help! Accidentally reversed polarity when jumping cable 2003 Lexus ES300
I almost forgot about this stupidity of my action because the car was running fine for 3 months. But it showed a series of problems. Stalling, misfires and DTCs. Fuses checked and the starter replaced and it was running for a while but eventually it wouldn't start at all. I believe what happened was electrical components were damaged to varying degrees and they failed one by one.
Given that, is there a way to identify damaged parts? For example, ECU, crankshaft position sensor, camshaft position sensor, ... This is where my knowledge stops. Please help!
FYI, I got Techstream and Mini VCI connector so I can see ECU is "responding" (not sure it's ok... how do I know whether or not ECU is intact?) but since I clicked on "Remove DTC" button a long time ago, it doesn't show trouble codes.
Full disclosure. Without remembering the stupid action, I thought it was time to replace ignition coils, which I did. That didn't fix the problem so I knew something went terribly wrong.
Also check if you have a Check Engine light when the ignition is in the ON position after you check all the fuses, because if don't, it would mean that you have probably fried the ECU. If it is on, try using your Mini VCI cable, or any other scan tool, to access ECU's live data.
Also check if you have a Check Engine light when the ignition is in the ON position after you check all the fuses, because if don't, it would mean that you have probably fried the ECU. If it is on, try using your Mini VCI cable, or any other scan tool, to access ECU's live data.
So, CEL turning on or DTCs being monitored, is that how one can tell whether ECU is working fine? It makes sense but is ECU supposed to quickly pick up some DTCs in the "crank but no start" situation like mine?
Of course, first thing first. I will check the fuses again. I see there are various relays too. How do I check them? (or do I need to?)
Have to check all fuses and go from there, and I mean all of them.
Originally Posted by willowcala
So, CEL turning on or DTCs being monitored, is that how one can tell whether ECU is working fine? It makes sense but is ECU supposed to quickly pick up some DTCs in the "crank but no start" situation like mine?
Of course, first thing first. I will check the fuses again. I see there are various relays too. How do I check them? (or do I need to?)
Will
Checked every fuse. No blown ones. Also, no DTCs found after meaningless and numerous "crank but no start" attempts. Going back to my original question, what would be the next step?
Check for spark, check for fuel pressure. Does the security light blink, and go out when you insert the key? Did you check the high current fuses?
No spark and fuel pressure good. (according to a mechanic after he replaced the spark plugs and the ignition coils.)
Security light acts normal.
Every fuse is ok.
When the engine is cranking, the tachometer needle doesn't move at all, which perhaps suggests the crankshaft position sensor is not functioning?
But no DTCs picked up by ECU. Communication between ECU and Techstream works.
I doubt that your crankshaft sensor, but to test it, you can simply disconnect it to see if the car will start, or you can also measure its resistance.
Originally Posted by fortitude
CRANK POSITION SENSOR
(a) Using an ohmmeter, measure the resistance between terminals.
RESISTANCE:
at cold 1,630 − 2,740 Ω
at hot 2,065 − 3,225 Ω
For me it seems like an ECU failure, since judging from the schematic below, besides some fuses that you already checked, your coils go straight to the ECU.
The best way to know for sure is to visit a local ECU repair shop and ask them to run a diagnostics on your ECU.. It is not a DTC check, they should take your ECU out and see if it functions alright.
I fixed it! It was a bad crankshaft position sensor. It was so difficult to get to it but I managed to replace it with a new one and then the car cranked and started without hesitation.
I think Toyota ECU has a problem in terms of logic or programming. If it had generated P0335 code, I would have solved the problem much earlier. (not to mention saving a few hundred dollars I spent on the other components)
Most excellent congrats. Shows how robust the electronics in these cars really is. On that sensor I've seen it go bad and NO codes were set this is an oversight in how the ECU is programmed.
02-23-20, 02:25 PM
Help! Accidentally reversed polarity when jumping cable 2003 Lexus ES300
