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The mkiv Supra Owners Club

Supra won't start


Tommyd16

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Wiring loom fault, alarm fault, crank sensor fault, igniter box fault, cam sensor fault (possibly), ecu fault. I would get a good garage to look at it, if they get it wired up for diagnosis prior to the no start occurring it should be pretty easy to see what's not happening. Are there any fault codes after a no start? If not I'd bypass the alarm for a start. If you don't know how to do it any auto electrician will do it for you.

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ok fully reset everything by leaving battery disconnected for ages. reconnected, removed the fuse to make sure ecu was reset. checked for codes and had nothing. made sure i got a decent bit of fresh wire. cranked it over and it didnt start. bridged the connection and got fault code 12 so i will get the fluke out!

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I would check the crank sensor bolts are not loose, do not over tighten them though! Then check the connector to the sensor pigtail is clean and properly connected. Then remove the ecu connector in the passenger footwell and check the sensor resistance there, being very careful not to open up and knacker the plug connectors. If high or low resistance follow loom to sensor connector pairing itself. Finally if these don't fix it get a good garage / auto electrician to put an oscilloscope on the crank sensor output at the ecu end, (back probe the connector), and look at the output waveform and amplitude. A dual or four channel scope will let them see how it's phased relative to the cam sensors, and thereby if it's moved. I doubt it's loose as the engine would probably run really badly and throw other codes. If someone was stupid enough to wire the immobilser into the crank sensor circuit then that could certainly cause issues. Unlikely unless real idiots have been involved. The checks sans the `scope can be done at home. Beyond that I would admit defeat and get the cheque book out.

Edited by Chris Wilson (see edit history)
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had a quick look before i started work (car is stuck in works car park until tomorow morning) mangaged to get an arm under the car to try an find the crank senor. i think i had it and the bolts felt tight, will properly when its home tomorow though and i can jack it up. tried to turn it over a couple of times and it was the same then the last couple of times the speedo neelde started bouncing and clicking behind the dash and when it stopped cranking the indicators flashed once??? cranking it has ran the battery down abit now andits about 11.3v so maybe this has something to do it?

will charge it fully tomorow and try and measure the resistance of the sensors. the indicators flashing makes me think the alarm could be at fault though

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The plug and socket were fine. Disconnected the sensor and checked the resistance of it and it was open circuit. Also checked the cam sensors and they were bang on. Removed the crank sensor and double checked it. Deffinaltly open circuit. Get the new one monday so will fit that and see what happens. This fault agrees with fault code 12 though. So much better now I have the car back at home with all my tools and jacks etc imageimage

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