avhart

Can anybody please take a shot at this to help me out? I know it may all sound pretty silly but what I have done so far is the honest truth. And the B+ problem for the FP is really not solved so I guess it can happen again at any random time leaving me stranded! Any suggestions would be welcome as I'm not all that experienced.

Could it be the big Circuit Opening Relay next to the ECU? Could it be some problem with the engine bay Diagnostic connector? Even though the ECU reads OK can it still have a problem? The ignition switch? Maybe something else I'm not thinking about at all? The actual FP circuit itself seems simple enough.

Thanks in advance...

Yamae

I worry that contacts of the circuit opening relay or the ignition main relay are shaped one side convex and the other side concave. When contacts are shaped like those, unusual relay problems occur intermittently. See attached PDF file of 1/2 and 2/2. Two PDF files can't be attached and I send you one more post to send you 2/2. Those relays are not simple and there are two windings. I suggests you to check how contacts are worn and increased the thickness seeing inside of those two relays.

Yamae

Here is 2/2 to add.

avhart

Received with a big thank you Yamae! The relays you mentioned are really not simple ones, as you said, and the Circuit Opening relay is very difficult to get new (expensive too). But are you also saying you can actually open the relays up to check the internal contacts? I never thought of that if so.

LeX2K

You can inspect the circuit opening relay and have a look but very likely you won't see anything unusual. My gut says your problem is the contacts the EFI relay plugs into, or farther down the wire like where the wires crimp to the terminals. Why not run a fused wire from the battery to the B+ terminal and see if your problem goes away.

avhart

Hi there LeX2K and yes, this is something that I have thought about but I didn't have to go there because I got back the 12 volts to the B+ pin (in the connector) after I checked the ECU with the jumper. I see where you coming from with the relay plug though so one of the troubleshooting things I did was spray CRC 2-26 into the plug and try as best as I could to clean inside the slits.

Yamae's idea of some kind of intermittent relay connection is also viable and something I thought about too but since everything is working fine now I am in observation mode. I will post an update if I get anything worthwhile. Thank you for your comments and I'd love to hear if you, or anyone, comes up with anything else because, as I said earlier, the problem is not solved and can return to bite me in the *** anytime from now.

Thanks

avhart

Well guys, it happened again! Drove the car fine, made multiple stops, put in gas and final stop was the grocery. When I came out the car refused to start. But now I know all kinds of stuff about that so first thing was to check the B+ in the engine Diag connector and what do you know it was a mere 0.35v. (as suspected). Well I didn't waste any time so I ran a 12v wire straight from the battery positive to the FP terminal in the Diag connector and drove home without further problems.

Next move for me is to buy another Circuit Opening Relay (058700-2300) and while waiting for that to arrive I'll snoop around the electricals and see if I can come up with anything to cause that problem. If anybody in the forum would like to chime in I'll be only to glad to hear any suggestions.

Thanks for all the help so far guys! I have been depending on this forum for years as I am my own major car fixer. Why you ask? Simple. First, I like it and I'm kinda ok skill wise and second, where I live in Trinidad and Tobago skilled techs for this kind and age of car are almost non-existent. So there, now you have it.

Thanks much again.

LeX2K

I would do this, maybe make it permanent. Alternative is start tracing the wires in the harness which isn't practical when harness is in the car.

avhart

Hey man, you hit the nail on the head. That's exactly how I was thinking. Now here's my problem, I have to look for a switched 12v supply to activate the pump only when the engine is running. This supply could be in the engine compartment or in the trunk (or anywhere else) and must be able to supply a continuous 20 amps (approx. fuel pump draw) or thereabouts. Any ideas where I can tap this off from?

LeX2K

The EFI relay is triggered by the ignition switch (this is where B+ comes from) so you could add your own relay. I still think your problem is the wires or terminals going to the EFI relay.

edit - circuit is similar to this

avhart

You just put me on another tack, my friend - suppose there is a fault in the ignition switch. I have had problems with it already. I will check that out tomorrow and let you know. We may be on to something there.

I'll post again soon, thank you very much. Thanks for the circuit as well. I have something similar but not as detailed as the one you sent.

Bottoms up...

LeX2K

What problems have you had with the ignition switch? The IG portion goes to all kinds of things in the car I'd expect you to notice other problems if the switch was flaky. Ideally when the car fails to start you would check for power at the EFI relay coil. One terminal is ground other comes directly from the ignition switch.

YODAONE

One simple way to determine if your ignition switch is at issue is to place your finger on the ignition switch dial.

If hot then you have excessive resistance in the circuit.

I noticed mine was warm, almost hot while extracting key after running 15 minutes..

Then I realized I had forgotten to tighten nut on the negative battery post cable...so attribute that to increased circuit resistance.

Check all negative cables and grounds points.

If original, you will find they all require attention, probably replacement.. especially the "AC Compressor Stay.

See:

https://www.clublexus.com/forums/ls-...ispreloading=1

avhart

Very interesting. You know a lot more about this car than I do. The problem I had with the switch was the little black tang that holds it in place with a screw broke off and I had a good time gluing it back in place with crazy glue. Other than that there are no other odd electrical things I I have noticed that would point to the switch. I just thought about it when you mentioned it. I will check the internal live contact on the EFI relay a little later on and see what we have there and get back with you.

Thanks

avhart

Hi Yodaone, long time no hear. Good tip and in my case the switch is not warm at all. On your other suggestion, i have already checked some of the ground points but I could never seem to find where all of them are! Like that A/C compressor stay for example (never heard of it). I followed the link you provided and there is a ton of good info there that I will check out later on today.

Thank you. I'll post the results as I get them.