barbio1980

Hi. Please be gentle, I am not mechanical, but determined. A week ago went to use my GX470 and no power. Dead completely. Pit on charger and went about the day. Much later was able to crank and go to store and return. Two days later (no in between use) car dead. No jump start helped. Put on charger overnight.
Next day, tried to reconnect battery and horn kept making noise. Not the usual noise for anittheft. Went thru googled steps of reset key or any other solution. Was able to get it to stop. Somehow. But now car would crank but not turn over. if I try more than once or twice it is as if the car loses power and I’ll hear only a click and dimmed lights.
-battery tested and even swapped out
-my fob does cause the flashing red light on dash to go out when I try to start but again, doesn’t turn over
-followed steps to find parasitic drain in meantime - it reads 1.85A unless I remove the EFI relay, then drops down to .6 or so. Relay changed already.
- all other fuses test fine in the car under hood and inside panel except ST2 and STA which I read won’t work until being cranked
- before all of this the fuel and speedometer gauge would intermittently work but no issues starting ever.

any advise?

NTH

Failed alternator?

barbio1980

I followed a guide to kind of bootleg “reset” ECU using safety clip in the 16pin connector thing. After that I was able to start so it seems like it is related to the anittheft thing still? Even tho it seems to recognize my key?
however, I turned off the engine, retested while off and it appears the EFI relay remains hot and 1.9 amps. When removed, stops back down. After testing this- I couldn’t start car again.

chiph9

The computer will stay awake for a few minutes after locking the doors. Try waiting then checking the draw.

Also, it's possible the relay is stuck closed. Dealer prices on the relays go from $25-80. Get the part number off your EFI relay and look it up. There are almost certainly Chinese clones, which I wouldn't use for the EFI relay (they're fine for stuff like the headlight relay), so I would order from an online dealer and get a genuine part.

Chip H.

IBallEng

Sounds like you are looking at a lot of things simultaneously. Try to focus on one thing at a time. Easy things first! Voltage, during the failures. Not just at the battery, check the connection in the engine bay fuse block too. This could be a bad connection, or terminal. Also please explain how you are checking current draw. As previously stated, there are levels of activity in the system which can fool you. I know you said the battery was tested, but if the voltage is dropping after a few cranking attempts, either your amperage draw is HUGE, there is a connection failure, or the battery is NOT good. I have over 40 years in the car repair industry and have seen numerous battery failures on NEW or TESTED GOOD batteries. I'm not saying you absolutely have a bad battery, just want to be sure. As for the Relay, I doubt that is your failure. In all my years I have seen a few relays go bad, mostly the pull in circuit fails and it just won't work. Corrosion can be the culprit too. But if's easy enough to swap it with another relay to rule it out.

Check voltage when you have the failure!

barbio1980

Thank you so much for answering. When I connect the meter between the negative post and the cable (with the key out) it starts at 2.25 or so and drops and stays at 1.85. When I remove the EFI relay, it drops. Will get exact number but below 0.5 for sure. I have tested every other fuse with a light up thing and asp the multimeter looking for a drop and only the EFI fuse and relay make a difference. My battery is from 2020 and autozone said it checked fine. But as an aside, while waiting for a trickle charge on the battery , I used my dads van battery with the same results here. We have fastened cables. No corrosion at connectors.
because I have to remove EFI, I guess, my car then seems to act like it doesn’t want to start. Cranks but doesn’t turnover. I use paper clip to diagnostic pin thing to reset ECU/ immobilized which takes 30 minutes to do with power (so says the video…) and it cranks just fine. Even before this the flashing red key symbol in the dash disappears when I insert so I am not sure what that is about. But I get it started and it dies in no time. In fact did so last night while I was an hour into trouble shooting after having been charged all night long.
not sure how to address the EFI issue from here.

IBallEng

I think what you are not understanding is that the EFI relay powers a lot of things, not just the fuel pump. Including but not limited to some of the computer circuits. Pulling the relay doesn't narrow your search enough. I have had a similar problem on a 3rd gen 4runner and it will blow the fuse, then when I go to check it the short is gone. This involves the 02 sensors MAF, Fuel pump, ECU and diagnostic port. Eventually I'll spend enough time on it to find the failure, but this is not a DIY project for a novice. Sadly it would take us months to trouble shoot by communicating this way. Unfortunately I would recommend finding a qualified technician to take it to. Sorry I couldn't be of more assistance.

barbio1980

For anyone else that comes along the thread, I absolutely understand it is beyond the EFI relay. Was merely pointing out the battery drain has been isolated to that point when asked how I had tested the fuses/ relay/ battery on a previous post.
I’ve read numerous threads describing clicking sounds at the relay but no sounds aside from the initial one at connection to battery.
Also read that the ignition switch may be bad, causing the relay to stay on when the key is out. Will look into this tomorrow when I can open it up.
If anyone else has any other suggestions, I’ll take it.

chiph9

My wiring diagram (for a 2004) shows that the EFI relay coil (pin 1) gets power from the ECU (pin 8 "MREL" wht/grn). Pin 2 is ground. Make sure that pin 1 drops to zero volts several minutes after removing the key and closing all the doors.

When the EFI relay is energized, it supplies battery voltage from the 20A EFI fuse (on relay pin 5) to relay pin 3.
The EFI fuse also supplies power to the ECU ( pin 3 "BATT" blu)

When energized the EFI relay (from pin 3) supplies power to the ECU (pin 1 "+B" blk, and pin 2 "+B2" blk),
and the C/OPN relay on pin 5 blk,
and the 10A EFI2 fuse (blk incoming, blu/wht outgoing)

The blu/wht wire from the EFI2 fuse feeds power to a lot of things.
- O2 sensor 1 bank 1
- O2 sensor 2 bank 2
- O2 sensor 2 bank 1
- O2 sensor 1 bank 2
- Emissions canister closed valve (rear of vehicle)
- Mass airflow sensor
- Evap valve

Since the ECU is getting power from the 20A EFI fuse all the time, it uses internal timers and logic to know when to sleep. If there are devices that prevent it from going to sleep (such as a door being left open, lights being left on, etc.) then it will cause a drain.

Suggest you pull the EFI2 fuse to narrow things down some.

Chip H.

barbio1980

Hi Chip

Thank you so much for the help.

Pin 1 does not return to 0. It stays 12 volts.

I see what you mean about pin 3 as it drops when the fuse is removed

so, we knew it was staying on, hence the 1.8-2amp battery drain. But still unsure how to determine source. I see what all the fuse and relay feeds, but I would suppose that now I need to find out what makes it energized in the first place and cause for sticking on?

since you mentioned pin 1 comes from ECU would that mean the ECU or some other component that it plays with?

(fuse still good/ relay still good. Just won’t turn off)

chiph9

> I see what all the fuse and relay feeds, but I would suppose that now I need to find out what makes it energized in the first place and cause for sticking on?

Exactly. And troubleshooting that is the hard part.
A common approach is to pull half the fuses and see if the draw goes away. If it does, replace half of the ones you took out and check again. If the draw comes back then you know it's one of the fuses you just added back. Repeat until you have it narrowed down.

But this still may not find the source of the problem. So you'll need to get a subscription to TIS and see if it has a troubleshooting flowchart for solving a draw (I don't know if it does).

Chip H.

Lexus4321

There's a relay inline between EFI relay and fuel pump.

To OP, what type of amps are there on a batt cable when the vehicle is off? Amp clamp or a 10A inline meter is needed. The amount of amps can help the diagnostics. You said 1.8 to 2 amps. Why the variance?
Also, 600mA is still a lot to be draining out of the batt.

What's the exact relay you installed to replace the old EFI relay?

The ignition has four states, 'off-lock', 'on-acc', 'run', 'start'. I wonder if your ignition has an issue with the 'run' state. If the ignition is always saying 'run' even when key is removed, that could keep some things (relays, etc) in the ON state. It's a possibility, but would be a rare thing.
See PDF #2 https://www.clublexus.com/forums/gx-...-charging.html


EFI relay is directly controlled by ECM , WHT/GRN wire, see PDF #1 and #2 https://www.clublexus.com/forums/gx-...e-control.html

To check and see if maybe the ECU control transistor went south, you need to test the amps on EFI relay pin #1 (in the socket, so remove relay). Using a 500ohm or 1,000ohm resistor, put the end of resistor in pin #1 socket (you might need to make a wire extension that has a blade on the end so you can just plug it in), inline the resistor with pin #1, then inline your amp meter between resistor and a ground point. Do you measure any amps (mA)? Don't turn ignition to START, you need the EFI relay for that to work, but you can test the mA on the #1 pin with ignition in the other positions.

If you get constant mA through pin #1 through resistor, then that issue is ECM related. If the ECM is using a NPN-PNP pair to control pin #1, if one of those are bad, it can cause pin #1 to stay 'on'.

One way to test if it's ignition switch related, measure voltage on EFI pin #1 (you expect 12v if it's stuck on), then yank the in-cabin AM2-30A fuse. This fuse provides the power to the ignition switch. With the fuse out did EFI pin #1 voltage change?

barbio1980

It’s been a while due to rain and an unexpected hospitalization so I hope you are still around. I followed your steps and the pin 1 from the ECM is on all the time as you described. When I found the bundle of cords that included the green and white wire that leads to that relay, I unplugged it and the amps being pulled dropped tremendously. From 1.8 to around .5 or less. I have to recharge and test this again in requires since the battery was left connected. My current question is this- is there a way to know whether this is an issue from the wiring itself versus the ECM? Before I purchase another ECM, I thought I’d ask.
I want to thank you all for the help. It has been so interesting and I have even gone back and read many other of your posts to learn about all of this. Happy to be nearing a hopeful resolution.

I should also mention that pulling the ignition fuse didn’t drop the battery drain. In fact I’d unplugged every wire from around the switch intended to try to replace that switch part that is mentioned on numerous threads here relating to EFI.