UTsleeper

Making a new thread since I made some assumptions about the issue before fully understanding the issue.

The car does have traction control.

Problem:
When turning the key to the ON position, the EFI Main Relay does not click on. I have verified this by removing the relay, turning the key ON and then reinstalling the relay. No clicks.
With this, there is no power to B+

If I jump pins 2 and 4 I will hear everything power up under the hood.

There is no CEL for diagnostic.

I have tried 3 different ECU's. One was out of a 90 with TRAC. The 2 I currently have are from a 92. 1 is with TRAC, the other is without. Behavior has appeared to be the same among all 3.

What I want to know:
Where is the best place to invest my time to try and diagnose this?
Are the any wires around the PS pump that could cause issues like this, or just major issues in general? (PO did a PS pump replace than the car quit starting)

What have I done:
Checked all fuses(I think) and replaced popped ones.
Swapped the horn and EFI relay for testing(same relay it seems).
Tried a few ECU's.
.....and probably a lot of random things I forgot.

Goal:
To get the car running so I can move it when needed till I pull the engine in a couple months.

dicer

You need Yamae to give his ideas on this. I'm too lazy to dig up the books on it. I could take a guess that maybe it does not activate until there is an rpm signal from ignition system. Does the fuel pump come on to initial prime the system when key is first turned on?

UTsleeper

I do not hear it prime the pump when I put the key in the on position. Maybe it's super quiet, but there is nothing blocking the sound and I hear nothing.

Yamae

You once have written below at another thread,
Above statement simply means that the EFI Main Relay is working good. There are conflicts among what you have been posting. How can I help you?

UTsleeper

What conflicts? I want to make sure I am relaying everything as to not waste anyone's time.

Would the 4 things(cam, crank, etc) stop the efi main relay from even turning on? From what I had been reading, it seemed like things like the B+ port should be working no matter what if wiring and such is in check. Without jumping the EFI main relay, there is no power on B+.

Just tell me what needs to be known and I will answer or do what is needed You guys have the knowledge, I am just impatient and keep trying **** lol.

Yamae

It seems to me that you are mixing the EFI Main Relay and the Circuit Opening Relay. Those two are totally different ones and have different roles. Both are important to run the engine and you need to know how those work to troubleshoot the starting problem. Without knowing and understanding those, it is almost impossible to get a result quickly.

UTsleeper

My assumption, based on my reading of various posts, is that when you turn the key to the on position, the EFI main relay(next to horn relay) should turn on and initialize the remaining components. Is this not correct?

Or is the path more like key ON, ECU, than that fires up the EFI main relay?

How things were behaving, it led me to believe that the EFI main relay is needed to even try to start. When I would not jump that relay, I would not get RPM's on the gauge when trying to start. The minute it is jumped, and you hear everything initialize, the tach works as expected.

I will continue to read the forums and see if I can find better answers. I have been doing searches in the past for efi main relay as well as current opening relay. If anyone has better suggestions for search criteria, if you feel this has been answered many times, then let me know what to search. Some posts go all over the place or end with no resolution, so for me that has made it difficult to find paths to check.

This is where I saw that the EFI Main Relay should be powered on with key on. Which then would power on the ECU. Old Thread (Edit here)

oldskewel

iTrader: (1)

This older post of mine has the circuit diagram for those relays:
https://www.clublexus.com/forums/ls-...ml#post9777959

From reading your other posts, I think you might benefit from getting a voltmeter as well. That way for example, when you find that the relay does not work, but when you jumper pins 2 and 4 everything works, you'll be able to confirm voltage on pin 2 directly (e.g., if that's what the ECU sets). Simplifies the analysis, helps by double checking things at a lower level so you don't arrive at wrong conclusions.

UTsleeper

So, tried to test the voltage at the ECU today. I unplugged the ECT(22 pin) connector on the ECU and tried to check voltage between E1 and the B/B1 ports, with no reading showing up. Is this something that needs to be plugged in when testing or should power be going there? And if I tested this right, where would the ground for E1 be located(I am assuming its a ground, correct me if I am wrong)?

I put the key in the on position after unplugging.

I started trying to follow the troubleshooting pages here.

oldskewel

iTrader: (1)

I would recommend staying away from the ECU. Leave that all plugged in. All the circuit measurements you need are available elsewhere (such as at the other end of the wire coming from the ECU). If you find a problem, while testing the rest of the circuit, that points to the ECU, then I would dive in there. But not before that.

UTsleeper

Any recommendations on what to search for to see other troubleshooting steps for checking voltages and such? I decided to try and check voltage to the ECU since there is no CEL with key on and it all quit working after the PO did the PS pump, so I am concerned that maybe there are wires there they screwed up.

I have looked at the diagram in the link you posted. When I was testing last night I was not seeing battery power on both of the EFI main relay ports. I will be checking that again today now that I have a new multi meter, but still has me wondering what is going on if only appear to be getting power on the EFI fuse side of the relay and not the ignition(if I am reading it right).

oldskewel

iTrader: (1)

I expect that circuit diagram is valid for your '92, but double check that.

Yamae is exactly right that you need to be very careful on not mixing up things like the "EFI Main Relay" on that diagram and the "Circuit Opening Relay" or the "Fuel Pump Relay." In many cars, the "Main Relay" also contains the functionality of the "Fuel Pump Relay" and you can get some wrong advice when people are discussing things without looking at the actual circuit diagram. I have found that understanding this diagram answers a lot of the mystery and errors you'll find floating out there.

If you think there is a problem with the Main Relay functioning, I'd find the relay, feel/listen for what it does when going from key OFF to ACC to ON. Probably no need to START for this troubleshooting.

Pull the relay out. Use your meter to measure the socket (the thing the relay plugs into, in the car). Check that one is +12V all the time (in the referenced diagram, the one at 11 o'clock). Another one (at 1 o'clock) is 0V (OFF) or 12V (ON) depending on the ignition switch. Key OFF, check that the one at 5 o'clock (in the diagram, you'll need to figure out which pin it is on the actual socket) has zero resistance to ground. Key OFF, check that the one at 7 o'clock has zero resistance (0.1 Ohm or less on your meter) to the +B pin in the Diagnosis port.

That just tested a bunch of stuff (and from the circuit, you can see it has nothing at all to do with the ECU). Any problems, keep checking. No problems, check something else.

I'll just throw in there that I once had an unexplained and never understood blowing of that 7.5A fuse that caused the starter to not run.

If those tests are all good, it means the Main Relay does not have wiring issues and is getting the power and signal it needs. and you still suspect the Main Relay, then to do that, you can:
(1) bench test the Main Relay - check for continuity (some resistance, maybe like 60 Ohms) across the 1-o'clock to 5 o-clock pins. The other pins should be open. Then connect a battery across the 1-5 o'clock pins. That should close the switch between the 11-7 o'clock pins. A 12V car battery should work. But I like to use a 12V cordless power tool battery for this testing, with little alligator clips to connect. A 9V battery, like from a smoke detector or OLD transistor radio should work too. You should hear the switch close, and the resistance across those pins should go from infinity to near zero.
AND / OR
(2) Jumper the pins in the socket to basically set that switch closed (current flowing). In theory a paperclip will do that, but it may get hot quickly. I use some household 12AWG solid copper wiring for jumpers like this, and flatten the ends with pliers or a hammer to make them spade-like so they fit in the socket receptacle.

If (1) shows a problem with the relay, and (2) makes things work, that is two votes for a failed relay. If (1) says the relay is good and (2) does not make things work, that says the relay is good, and points to something else being wrong, so follow the problem downstream with more tests. (1) fail + (2) fail would mean you've got a failed relay AND a problem elsewhere, which is very unlikely to be true, and I'd recommend re-doing the tests. (1) good and (2) makes things work means there is something probably wrong with the (1) test. The relay may be bad.

Many times these relays can easily have their covers popped off so you can inspect - look for burned contact points that may be causing resistance, or failed solder joints.

oldskewel

iTrader: (1)

Covered in my immediately previous post, but you should see battery voltage on one port all the time (only a bad battery, the fusible link, 20A fuse, and of course any connection failures along the way should be able to stop that).
The other one should show 12V as long as you've got a good battery, good 30A fuse, the ignition swith is set to IG2 (the second position, where 0 is OFF, 1 is ACC, and 2 is ON), and that 7.5A fuse (probably in the driver's footwell fusebox) is intact.

UTsleeper

So, I have battery power to pin 2(think that is how it is labelled on the relay) with key off or on. This is expected.

There is no power to any of the other 3 pins on the fuse box when the key is in the on position.

I checked the AM2 fusible link and even removed/installed. No blown element inside.

I checked all of the 7.5 fuses under the dash(didn't have a diagram). None were blown out and there were 4 there. I switched all of them around just in case maybe 1 had an issue that wasn't visible. I could just go through and replace them all if anyone thinks it will help.

Normally I would jump to ignition switch here, but I think we can rule that out since the dash comes on.

Any suggestions on the next step? Am I going to have to start checking wiring at this point?

UTsleeper

SOLVED!!!!

And sadly, disregard some of the troubleshooting lol.

After my last post I went back out to the car with a test light to see if current was getting to both side of the IGN fuse when the car was in the ON position. Problem was, the test light would flicker. Turned out it was flickering to the movement of the fuse.

I then got out from under the dash and just pushed on the fuse and I noticed the CEL light come on and heard clicking under the hood. Started right up after that!!!

Thanks for all the help. The diagram helped alot, just not in the way I expected lol.