JohnW420

1995 Lexus LS400

Ive spent the last 2 weeks trying to figure out what the hells going on, ive researched and read so much and watched so many videos with no luck so its time to give up and ask the forums. plesae dont tell me to search it cause i have for many many hours.

As the title states im in a crank no start situation. I'm getting spark coming off the driver side coil but not the passenger. I tried switching the coils with the same results and i switched the ignitors with the same results always driver side sparking never passenger. Ive looked up a bunch of videos for testing the cam and crank shaft sensors and they all seem to be up to spec, but my knowledge and experience with multimeters is none soo ya. I was thinking of going to get a new crankshaft sensor first cause theyre much cheaper and easier to access.

Any knowledge or input at all greatly appreciated, as im doing this on the lowest of budgets I got laid off the day my car broke down and i didnt make it to work

deanshark

Just a thought but how are you checking for spark coming from the coil? The original coil wire? If so then maybe that wire is bad.

JohnW420

My friend also pointed that out so i just to see what would happen tested the ohmns on the 2 coil wires and the working side read twice the number as the other side so I'm ordering new cables and hoping that works

JohnW420

So i changed out my cables and still doesnt start D': so if im correct all thats really left is the sensors. I took a test light to the crank shaft sensors port and its reading a ground in both sides. that isnt normal is it???

dicer

You forgot the basic stuff to start with when asking here. What year car? That some times makes a huge difference in the help here.
Yamae is the best to help on this one maybe he will see I put his name here. I can give some ideas but I only have manuals for the gen 1 stuff. If you have an OBD2 year car it can make the diagnostic much easier, but a person will need a 1000 plus dollar scan tool. So then its either pay for a good diagnostic or just do the guess work deal, since I'm sure you don't have a decent Oscilloscope to look for the various signals, you will need the tools and the schematics and trouble shooting info. For a reasonable price you can get that from the Toyota tech site. Go to youtube and look for the testing the ignitors video, but you said you swapped them and its still one side? It could be the driver transistors in the ecu that are bad for that one side. It could be the position sensors too but that should throw a code. Have you checked for codes? Again depends on the year car how to do that. It could also be rodents chewing wires I have had that problem recently on a Subaru, talk about maddening stuff, just making work I didn't want.
Checking connections and wires, grounds etc is a good idea too. It could be a bad coil on the one side or bad primary to the coil. Old crusty wires and connectors you know.

JohnW420

oh sorry its a 1995 lexus LS400, editted first post too

as for codes nothing comes up with my cheap little code reader but i have my friend bringing his expensive around hopefully tomorrow. Im playing around with the multi meter and all the wiring but im clueless with this thing so jsut trying to watch video about it all and stuff

Yamae

It would be better to use a good scanner but without it, there is a way to check whether the ignitor is properly driven by the ECU or not.
Check the drive signal IGT and IGT2 using an oscilloscope if possible. Without it, you could use a DVM measuring the average voltage there. Can you observe the similar signals at terminals pin #2. Attached below is for a 95 Celsior and some characters are in Japanese but those 2 rectangles indicate ignitors. You should get the same voltage readings at IGT and IGT2 while cranking. If not the same, it simply means that one igniter is not properly driven by the ECU or the connection is not OK. Sometimes ignitor's input port is damaged and in this case, you need to check it by the difference of the resistance.

JohnW420

Sorry for the late reply, tried to get one of those mobile mechanics to diagnose it with zero success. The guys clueless and just trying to milk me for money.

I will be doing this ignitor test asap here I will let you know results

JohnW420

So i the test at first i just probed the T pin second one in, labeled on the ignitor as T, into the dissconnected harnesses both read 0. So then i tried using a paperclip to get at it from behind so i could test while plugged in and both read 0 again. am i doing something wrong here? I've also completely lost any spark

EDIT: So i just found out some coolant sensor that sits behind one of the coils was completely split in half

Michael88

I just have to share this. It is absolutely mandatory that you disconnect the battery when changing any wired part on a Lexus. The computer gets very confused when things are unplugged. For example, on a 98 you have to unplug the MAF sensor on the air intact ducts to plastic vacuum box on the passenger side. I imagine you have already disconnected the negative battery cable and let it set for a minute to reset the computer. If not, do it.

JohnW420

Update!
So i did the Ignitor ECU bypass (for the seccond time) test shown on that one youtube video a lot of people mention. and it the test actually worked this time I got spark out of both wires =D. I have yet to attempt starting the vehicle as my coolant hoses are disconnected because i found out that the coolant sensor was rotten through and snapped. its sunday so i cant replace it this second but heres hoping she starts when i try

Michael88

Does you 95 have the key and key fob as one unit? Is your key broken or cracked from the plastic housing? If so the proximity security will cause a no start situation. The key has to be intact.

JohnW420

I've only ever had 1 key which is pretty basic but there is an aftermarket compustar fob/car starter. Which I did not get installed but it's always worked just fine. If My car doesn't start after I get the coolant sensor from rock auto I'll try just unplugging the main compustar box from underneither my steering wheel see if that changes anything. I'll also pick up a can of starting fluid now that I've seen spark, at least with the bypass test

dicer

And you do have fuel pressure?