The last time I drove the car was October 10th 2010. I never had any problems with this car and have not experienced most of the common problems, wear and tear associated with this car. No engine mods, just suspension and exhaust.

This morning the car just cranks but does not turn over. All fuses and relays are working, fuel pump is working, battery is strong and has plenty of juice. I ran a CEL check and found out I have a code 12 CEL (RPM Signal circuit no. 1). I have searched the forums and checked the following: wire harness from the crank angle sensor, (2) cam sprocket sensors, (2) coils are intact and does not have any breaks but there are no sparks coming out via timing gun.

My suspected bad components are ignition coils, igniters, and ECU. It may not be all of them but I will isolate the problem to these components. The car has approx 160k miles. Its weird that this happens all of a sudden without any symptoms.

I need spec sheet parameters with procedure for testing the following components mentioned and or if anyone local with a similar year car in good running condition can help out in swapping components for test purposes would be great.

If you guys have any other suggestions please let me know. Thanks in advance.

 

where you at in socal?

what do you mean it cranks but doesnt turn over? ie-no combustion/not catching? (cranking=turn over) any recent work done to the car? is it stored inside or out? (relevant since you can have little varmints chew up wiring when left outside)

 

Thanks PD.

I'm in South Bay area.
It cranks but will not start because no spark to create a combustion.
No recent work done or performed on the car.
It is always garaged inside and have checked the wiring harness related to CEL code 12 as document here in the forums.

 

The "crank" sensor aka Engine Speed Sensor has no resistance value so I think its broken and this may have been the cause of CEL code 12 as it is one of the components mentioned on the diagnostic manual. Can the Engine Speed Sensor be also the cause of not producing any spark?

 

Upon checking the wiring diagram and reading on the operations of crankshaft position sensor (crank angle sensor or engine speed sensor), this sensor is necessary for triggering spark in conjunction with the cam position sensor, igniters, and ignition coils.

I have ordered the crankshaft position sensor. I hope this will solve the problem.

 

good luck!

 

should work.

 

Crossing fingers.

 

She's alive!!!

Just an FYI y'all. It was indeed a bad crank angle sensor... Just to make sure, we tested the new one vs the old one. The new sensor we purchased was within spec (1.2Khoms). The old sensor was 2.0Mohms and continuesly climbing up to 4+ mega ohms.

Next is to do some tuneup. Purchased NGK wires and Iridium IX plugs.

 

good stuff

why the iridium IX i'm curious?

 

It's mainly for the price. I was going to get the OE NGK platinum plugs but it cost $7+ and the NGK Iridium plugs also cost $7+ each too so I opted for the upgrade, durability, reliability, and mileage. I stayed with the stock plug "heat range" rating also. I got all of these through Amazon.com

 

hmm.

i run copper plugs (NGK V-Power), about 2.50 each or so at autozone.

don't last all that long (since they're not platinum/iridium), but produce a much better spark, plus plugs are a cake job on the 1uz lol.

 

Hey PD... Yeah, the V-Power are only 2.89 each. I guess as far as the cost goes from V-Power vs Iridium its probably about the same. You would probably replace the V-Power plugs 2-3x sooner before replacing the Iridium ones right? There is a big debate about this specially on the SC3/4 section. I suppose the cheapest one is ok for daily driving but majority voted not to use anything less than what factory suggested.

The user manual recommended this (BKR6EP-11)
http://www.ngk.com/results_app.asp?AAIA=1187489

NGK Double Platinum 2978 - BKR6EP-11 .044 DOHC $7.83

It is in the same class (PREMIUM CLASS) as the Iridium IX and cost the same. Saved about 43 cents from Amazon including all the other goodies (NGK wires, plugs, crank sensor) with free shipping. I believe the total savings was more or less around $150

I agree. Very easy to change the plugs. It sure is a whole lot easier on my 99 SC4 than my brother's 93 LS4 tho as I have more room/space. Its quite a bit of work on his car having to remove a lot of the covers hahahahaaa...

 

i didnt do it because of the price, but because of a LOT of reading up. simple fact is that the copper plugs produce a better spark, and promote better combustion through the chamber at all RPM.

 

Seems to be a another whole debate.... With those reading, is that specifically about your 99 LS400 or just in general? My main question would be why would factory (written on the manual) recommend the Double Platinum vs the V-Power? There has to be a big reason why right? I'm absolutely clueless at this point. Any idea? Don't get me wrong, I agree with what you are saying having a better spark which is good for the engine. Does it really produce a better spark over Iridium plugs or even to what the factory user manual suggested?