Crank no start - yes, another (1 Viewer)

[Jeeper]

Here we go again.. 97 LX450

Very familiar with the fusible links, EFI fuse, EFI relay causing this. My situation:

- Had issues with no CEL, crank, no start condition
- was able to wiggle the fusible links and get it started - figured the fusible links were going out
- replaced fusible links with new ones
- now same: no CEL, crank, no start
- swapped ECU, Fuel Pump relay, fuel pump resistor, EFI relay, Circuit opening relay, and more - no change
- Have 12v at the B+ terminal on the diagnostic connector with Ignition ON
- If I pull either the Circuit opening relay, the fuel pump relay, or unplug the fuel pump, I get a CEL with Ignition ON
- If I apply 12V directly to the fuel pump relay, pump runs fine
- I have checked wires at the EGR pipe - all appear good

- I do NOT have 12V on the yellow wire (B+) at the ECU, but I do have 12v at the B+ terminal in the diagnostic connector
- ECU does have 12v at BATT and IGN

- I have not checked the ignition switch, but it appears to switch IGN 12v power to ECU correctly, and I have a good CEL when fuel related items are pulled.
- Can the starter cut relay fail in such as way that the starter works, but not the power from the ECU to the COR/fuel pump? Doesn't seem so from the diagrams, but I'm running out of ideas
- Anyone have a pic of this EC ground point, seemingly under the intake?

Before thoughts of selling the one I've had the longest (15ish years) take over me.... suggestions?

 

[BILT4ME]

Do you have an alarm system on this truck?

If you do and it's an RS3000, Rip it out.

 

[MickeyB]

How did you get fusiable links. Toyota shows discontinued

 

[FMC80]

How did you get fusiable links. Toyota shows discontinued

Not discontinued.

 

[Rusty]

This isn't likely to be your problem if your fuel pump is running reliably when you apply 12v to the FPR, unless you also changed your fuel pump...

I recently thought I was about to lose my mind - my pump quit so I replaced it with an OEM Denso. Afterward I drove it for a few days and then one day it wouldn't start. Conveniently it died in the driveway which was lucky for me because at that point I didn't have time to deal with it. I tried it a few days later and it started. I drove it again (not far from my house because I didn't trust it), parked it in the drive and once again the next day it wouldn't start. Checked the FP and EFI relays, pump resistor etc. etc. and found nothing wrong.

I started digging here on 'Mud and came across a post that sounded like my issue and as it turns out the problem was with the new Denso fuel pump. The pins in the connecter were undersized, or at least they are slightly smaller than they used to be and they don't make reliable contact. You couldn't tell by looking at it the pins that they were any smaller, but I figured I had nothing to lose. The poster of this particular thread said that he had to deflect the pins so that the contact was improved. This turned out to be my problem as well, I had to bend the female side of the connector so that it made good contact with the mating half. IIRC the female half is on the harness side of the plug.

After I bent the connector pins I took my Cruiser on a fairly long off-road trip, confident that I'd solved the problem. I started and stopped the engine many times that trip and it worked flawlessly. When I got home I parked it in my driveway and again the next day it wouldn't start. I pulled the fuel pump and took another look, amazingly I had actually bent the female side the wrong way, somehow it worked repeatedly on that trip (thankfully). After a more careful look I bent the pins the correct way, reassembled and I haven't had a problem since. I'm just glad it didn't quit on me in the middle of nowhere, lucky that every time it gave up it did so in my driveway.

 

[BILT4ME]

How did you get fusiable links. Toyota shows discontinued

You need to look at a different Toyota parts source.

 

[jonheld]

If you're getting +12 at the diagnostic connector but not at the ecu E7 pin 12, then connector IL1 pin 22 is open or faulty.

 

[Jeeper]

If you're getting +12 at the diagnostic connector but not at the ecu E7 pin 12, then connector IL1 pin 22 is open or faulty.

Thank you @jonheld. For being the expert on this issue, posting EWDs online, and responding quickly. The 80 series world will be grateful for your expertise for years to come.

While I had back-probed this connector earlier as it's the only connection between the diagnostic connector and the ECU B+, this morning I left the key ON and wiggled/pulled/pushed the entire IL1 connector assembly. It is 100% the problem. CEL came on and then off. Will pull apart this afternoon and check crimps and terminals. The fuel circuit was a red herring and wasted a bunch of time.

Great to have confirmation on where to spend diagnostic time. Thank you again -

 

[jonheld]

Thank you @jonheld. For being the expert on this issue,

The only thing I'm an expert at is annoying my wife. I am second to none in that area.
I just read the schematic based on your findings.