97 LX450 No Spark, Could use help.

[sandcruiser80]

Check the blue wire and make sure it's not broken, at the distributor, also check the wiring near the EGR to make sure it's not melted.

You have RPM movement on crank with the gauge?
What about with a scan tool, does it show the RPM's moving when you're cranking?

CRANKSHAFT POSITION IS DETECTED BY THE CRANKSHAFT POSITION SENSOR AND THE PICK−UP COIL INSTALLED INSIDE THE DISTRIBUTOR. THE CRANKSHAFT POSITION IS INPUT AS A CONTROL SIGNAL TO TERMINAL NE2+ OF THE ENGINE CONTROL MODULE, AND ENGINE SPEED IS INPUT TO TER

I'm just trying to establish if there is a tach reading at all.

So I did some digging last night and here's what I got so far...

The tach does move when cranking, now does that equal RPM from the crank sensor, it does not appear to. However, I needed to put slow mo on my camera to actually verify the movement.

View attachment 2662115

View attachment 2662114

However, what it does have... is an RPM signal, even in a cheap off the shelf scanner that costs less than $100.

The crank sensor has a brown wire, a blue wire (known to cause problems at ignition coil connector) and a white wire with black tracer.

@ I20 ( apparently behind the glove box ) the blue wire splits from there to the ECM and the distributor.

Hook up a cheap scan tool and see if you have RPM signal.

For reference I disconnected my distributor and had NO RPM signal on cranking.
Video - 2021-05-01 13.53.04-1.mp4 - https://www.dropbox.com/s/2vcmvwiry0p6v5q/2021-05-01%2013.53.04-1.mp4?dl=0

Reconnected distributor, disconnected fuel relay, HAD RPM signal on cranking.
Video - 2021-05-01 13.58.50-1.mp4 - https://www.dropbox.com/s/pj484g08xb54i3y/2021-05-01%2013.58.50-1.mp4?dl=0

Reconnected fuel relay, disconnect crank sensor harness, HAD RPM signal on cranking, vehicle started.
Video - 2021-05-01 14.06.36-1.mp4 - https://www.dropbox.com/s/bj7q4mb9e9xur95/2021-05-01%2014.06.36-1.mp4?dl=0

NO RPM on scanner? My money is on Distributor or broken blue wire or melted wires near EGR.

Being as my truck started with the crank position sensor disconnected completely.... I would say if your truck isn't starting and has no RPM signal, check blue wire @ distributor connector, perform amp load test on wire, all checks out? Replace distributor.

I have RPM movement on the scan gage. It only cranked over 2 times cause the battery was pretty weak after sitting for this long and lots of cranks over the past week. It read 77rpm briefly on my scan gage

 

[rdcnj]

I have RPM movement on the scan gage. It only cranked over 2 times cause the battery was pretty weak after sitting for this long and lots of cranks over the past week. It read 77rpm briefly on my scan gage

Put new or freshly charged battery in whenever the time comes.

But I would check amp load on the blue wire and possibly scope it to see the pattern.

If amp check comes back good, it's very likely the distributor is bad, but you may want to disconnect the CPS (Crank Position Sensor) from the circuit and try it without it connected. A bad CPS could be also backfeeding a bad signal and causing the vehicle not to start.

Make sure you wiggle the distributor connector when doing the amp test. As stated earlier by Jon, it's a cheap connector and a likely culprit.

My video above revealed the vehicle does not need a connected CPS to run.

 

[sandcruiser80]

Put new or freshly charged battery in whenever the time comes.

But I would check amp load on the blue wire and possibly scope it to see the pattern.

If amp check comes back good, it's very likely the distributor is bad, but you may want to disconnect the CPS (Crank Position Sensor) from the circuit and try it without it connected. A bad CPS could be also backfeeding a bad signal and causing the vehicle not to start.

Make sure you wiggle the distributor connector when doing the amp test. As stated earlier by Jon, it's a cheap connector and a likely culprit.

My video above revealed the vehicle does not need a connected CPS to run.

Well I finally got some time to do some test and it still won’t start.
I’m getting RPM movement at 77rpms while cranking.
Traced blue wire from CPS to harness and it’s good. I have had my EGR disconnected since the rebuild and Iv had the harness all wrapped up and checked the wires when I had it all apart. Blue wire from distributor is good
I’m getting 15 amps while cranking on the blue wire at the distributor without the CPS connected. My CPS is leaking a bit so the one I ordered is not a loss really but now it looks like I might be ordering a distributor also.

 

[sandcruiser80]

Well I finally got some time to do some test and it still won’t start.
I’m getting RPM movement at 77rpms while cranking.
Traced blue wire from CPS to harness and it’s good. I have had my EGR disconnected since the rebuild and Iv had the harness all wrapped up and checked the wires when I had it all apart. Blue wire from distributor is good
I’m getting 15 amps while cranking on the blue wire at the distributor without the CPS connected. My CPS is leaking a bit so the one I ordered is not a loss really but now it looks like I might be ordering a distributor also.

 

[rdcnj]

Amp test is not to check how many amps are moving through the circuit while cranking, it's more about putting voltage through a circuit and using it to light a headlight bulb at the end of the circuit.

Just an FYI as I'm not sure how you got a 15 amp reading out of that wire, that seems abnormally high.

The proper name is "load testing an electrical circuit". That's how you determine the wiring and connections are good from one point to another.

https://support.alldata.com/sites/main/files/file-attachments/electrical_circuit_testing.pdf