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NO SPARK

Tiny
PEARLHICKORY
  • MEMBER
  • 1992 LEXUS LS 400
  • 277,000 MILES
Hi Guys, 1992 Lexus, v8, no spark any ideas, not very familiar with the Lexus, not getting spark, Ive checked relays and fuses, all seem ok, no voltage at coil packs, power supply to ignition? Does it have separate component to power coil packs? I was about to look at the crank position sensor, the car starts at times and wont other times, . Any help greatly appreciated, thanks.
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Wednesday, October 10th, 2012 AT 1:42 PM

23 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If either the carnk or cam sensor is bad the car wont' start so check both or actually all as you have two cam sensors.
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Wednesday, October 10th, 2012 AT 4:36 PM
Tiny
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I got the crank sensor out, any particular steps to test the sensor? I hooked up my meter, im getting 1100 ohms, I looked up the average reading should be 2200 to 5000 ohms, correct me if im wrong, what about the cam sensors? Any readings I should be looking for thanks.
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Wednesday, October 10th, 2012 AT 4:44 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It may be the cranks sensor as the ohms are low but if it's cold that may be why. We havn't any specs for those. But they should have ohms as well.
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Wednesday, October 10th, 2012 AT 4:50 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
If you don't have battery voltage to the coil packs, you are not going to start the engine. Sine problem is intermittent, you caould have a faulty ignition switch or an intermittent break in the circuit due to a loose connection somewhere.
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Wednesday, October 10th, 2012 AT 5:18 PM
Tiny
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I got the part about lack of voltage to coil packs ive looked over most wiring looks ok, im fixing to pull cam sensors out and test them, I found a source telling me I should have between 800 to 1400 ohms on the sensor and to do a voltage test also, with sensor connected and motor spinning.
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Wednesday, October 10th, 2012 AT 6:43 PM
Tiny
KHLOW2008
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Did you check for trouble codes?
The cam sensor should be 950 to 1250 ohms for your model.
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Wednesday, October 10th, 2012 AT 6:50 PM
Tiny
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No codes, im trying to locate the cam sensors, cant see them.
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Wednesday, October 10th, 2012 AT 7:31 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
They are in distributors. Also check the ignition relay it may have a bad ground goind to it and not allowing power to the coils.
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Wednesday, October 10th, 2012 AT 7:32 PM
Tiny
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Cool, I thought I was missing something here, so behind the distributor, last check I did was for voltage output on the crank, had around 600 milliamps, looks like a good reading, so off I go to distributors and check for bad ground on relay, thanks.
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Wednesday, October 10th, 2012 AT 7:48 PM
Tiny
HMAC300
  • MECHANIC
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Could be inside the dist too.
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Wednesday, October 10th, 2012 AT 7:50 PM
Tiny
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Ok, I was able to see the driver side sensor, it read 1125 ohms, the passenger side was open circuit, fluctuated a bit then back, to open, and its the one thats worse to get to, havent checked anything else yet, should he be condemned, [ replaced yet or keep looking ] will it start with only one cam sensor working?
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Wednesday, October 10th, 2012 AT 8:36 PM
Tiny
KHLOW2008
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It might but would require excessive cranking time. The fluctuation of readings could be due to the probes not getting correct contact and you should reconfirm the testing again.
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Wednesday, October 10th, 2012 AT 8:49 PM
Tiny
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I found one issue for sure, the passenger side cam sensor lead is split, only one lead is attached, other is cut and looks been like that a while, could it have still been making conductive circuit being very close, the car started sometimes then wouldnt, I had probes in there good, ive worked meters long time, finally wouldnt start anymore, I imagine could also have other issues.
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Wednesday, October 10th, 2012 AT 9:06 PM
Tiny
KHLOW2008
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Splice back the wire and test if it works. If you had checked for trouble codes, the cam sensor should have come up.
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Wednesday, October 10th, 2012 AT 9:44 PM
Tiny
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Will do, im calling it a day, ill splice it up, and repost in morning, thanks a lot for all the help, maybe tomorrow get it running, have a good evening.
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Wednesday, October 10th, 2012 AT 11:05 PM
Tiny
ASWAZER
  • MEMBER
  • 1 POST
Hey I have Lexus 1996 ls400 one day I came home and let my car sit overnight then started I think up in the morning it started the night 30 seconds late reply turned off I tried starting it back up and it cranked but wouldn't start. I had a mechanic look at it he thought it was the fuel pump and fuel pump pump relay we checked and replaced and it's still doing the same thing it just cranks but is not getting any spark any thoughts?
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Sunday, June 4th, 2017 AT 12:50 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,878 POSTS
Hello,

It sounds like the crankshaft angle sensor has gone out which is common for those cars. Here is a guide that will give you an idea on what you are in for when changing the sensor out and a diagram (below) on where it is on your car.

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

Please let us know what happens.

Cheers, Ken
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Tuesday, June 6th, 2017 AT 2:39 PM
Tiny
GYMGUY
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  • 3 POSTS
Car will not crank if crank position sensor is bad. Yours is good based on your measurements. Cold resistance 835 to 1400 ohms for your model. If CPS is good it may crank but if camshaft position sensor(s) are bad there will likely be misfiring. You should rule out spark issues first. A good video on how to simply do this shown on YouTube.
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Wednesday, February 27th, 2019 AT 8:09 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Can will not crank over (starter operation) if the crankshaft sensor is bad?
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Wednesday, February 27th, 2019 AT 10:55 AM
Tiny
GYMGUY
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  • 3 POSTS
Starter will try but engine won't start. The Crank position sensor provides no feedback to the ECU so it thinks the engine is not turning and hence will not spark or pulse the injectors. The Cam sensor will allow engine to run. However, if you turn the car off it won't restart until you replace the Crank sensor.
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Wednesday, February 27th, 2019 AT 5:40 PM

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