Automotive electrical help. Buttoning up an engine swap trouble shooting some final issues

[LexusLover]

So I just did an engine swap on my 2004 Lexus Rx330. I have a few posts up and around about the ordeal.

But I finally got the engine to turn over and she sounds great but I have some electrical gremlins that I need to figure out.

During the process of getting her turned over I had some leaking fuel injectors. Myself and my helper had the plenum off to isolate which ones were leaking and then after replacing the damaged o rings he cRanked it to make sure they were no longer leaking but the engine combustion backfired through the intake ports and ignited the little puddle of fuel on the intake manifold. I ran inside as fast as my chubby *** could and grabbed the fire extinguisher because my third helper my fiancé didn’t realize I wanted her to grab those and instead went to get the water hose which was useless, but she tried.

Anyways some of the plastic connectors are a Little melted and one of the connectors on the vacuum harness (a solenoid connector part 90980-11149 ) was completely melted and I have a replacment coming in. But some of the sheathing to some of the wiring also looks like it might have been damaged and the wiring is more rigid.

But I have a full spare harness that came with the salvaged engine so I can cut, and solder splice the full sections that need to be replaced if they indeed do.

However I’m wondering exactly how to go about this? Can I pinpoint t where on the harness the short could be using the multimeter, battery and the fuse box? Someone I am getting decent advice from on club Lexus has told me to look into the E4 section of harness on my wiring harness (since I’m also having a code for the heated circuit of my bank one sensor 2 oxygen sensor p0037)

Some more info on the issue. The first day we got the car running we charged it for an hour plus and then turned it off and the car started up 4 times with no issues besides having no car horn and no sunroof functionality. The next morning it started but there was no radio and the battery light came on and the lights on the instrument panel cluster began to flicker and go in and out. Then when we turned the ignition off the car would not start again. We had the car jumped later that day by triple a and he checked the alternator which appears to be in working order and also saw that the battery had just under 10v when he left after the car was running for 15 minutes I checked the voltage again with my little craftsman obd and the voltage was jumping between 6.8-7.1

So could a short have killed the battery and would putting a new battery in be a dumb idea since the main issue may persist and kill cells in the new battery?

Also how can I pinpoint where the short could be with only a multimeter and not one of those beeping short detecting doohickeys?

Any guidance and advice was greatly appreciated! Thanks

 

[garfunkle24]

You must have a serious drain on the battery, likely the short you're looking for. I doubt it's a direct short to ground or you'd be blowing fuses. You're in a tough spot because you don't really know if the wiring issue is related to the fire or not.

I would start by checking the draw at the battery and start narrowing the issue down by pulling fuses until the draw goes away.

 

[kd3pc]

check for warm spots on the wiring harness. IF the alternator/charging system is good, you should nave +12.5vDC at the battery. Check for proper grounds as well.

 

[dave*99]

Disconnect the battery before walking away until you are convinced you have this sorted. Don't need a fire at this point.
Is there a cable to ground the engine to the frame? Odd things happen if all the grounds are not in place.

 

[LexusLover]

You must have a serious drain on the battery, likely the short you're looking for. I doubt it's a direct short to ground or you'd be blowing fuses. You're in a tough spot because you don't really know if the wiring issue is related to the fire or not.

I would start by checking the draw at the battery and start narrowing the issue down by pulling fuses until the draw goes away.

I’m getting a multimeter tomorow. Will start checking fuses one by one

Is there a possibility the battery is just gone to **** for sitting in the basement for a couple months?
I would think a short in the harness leading up to an injector or coil pack would cause a misfire code but I don’t know enough about electrical.
Maybe I’m wrong but the only logical thing the short could have been caused by is the fire since everything was fine before I started the swap.
Also I might have blown the horn and sunroof fuses I also have a p0037 code and I was told that wiring connects to the E4 section of the engine harness which connects to the injector and coil pack wiring so it could be interconnected.

check for warm spots on the wiring harness. IF the alternator/charging system is good, you should nave +12.5vDC at the battery. Check for proper grounds as well.

what if the battery is bad and just won’t hold a charge? As I said the triple a guy who was here said the alternator was functioning so by my thinking it’s either a bad battery or a short in the harness?

Disconnect the battery before walking away until you are convinced you have this sorted. Don't need a fire at this point.
Is there a cable to ground the engine to the frame? Odd things happen if all the grounds are not in place.

So maybe I’m reading between the lines but are you saying that just having the grounds attached to metal is not proper and they have to be in the exact place they are meant to be? I may have one of the grounds coming off the Top left corner of the engine attached to a metal brace on top of the plenum instead of the chassis. I’m going to make sure I have that where it’s supposed to go.
Could improper grounding be causing This issue? Or is that unlikely and the probability of causation here more likely to be 1-shorted connection caused by melted wire sheathing / damaged electrical connection or 2-bad battery

 

[kd3pc]

the grounds become the Zero reference for the 12 vDC system, all of the grounds want to be at the same electrical point.

What is the voltage of the battery sitting? then meter a few spots on the harness to make sure all the grounds are at Zero volts. If you can get a meter that measures current and insert it in line, that will show how much current is flowing at various parts of the harness. Ideally when the car is just sitting, key off....should be close to Zero Amps and a solid 12vDC.

 

[dave*99]

The entire vehicle is full of sensitive electronics that depends on the grounding system to keep a zero volt reference.
So put the grounds where the manufacturer had them to be sure the sensors work properly.

 

[Noltz]

So I'm an automotive mechanic, strong in electrical, and I'm struggling a little bit understanding this situation. Why was the engine being changed? Was the vehicle running on the old engine? What did the new engine come out of? Was it complete?

The vacuum harness connector is probably for the evaporative emissions system or the variable intake manifold solenoid controller. A 2-wire connector is rarely used on a sensor. I can't think of one on a RX. If you tell me the color of the wire & it's tracer I can look on my diagrams and see if I can tell you what it came from. Your charging issue is a separate issue. And ^^ Dave there is right; ALL your grounds must be connected before you start diagnosing issues like this.

 

[LexusLover]

So I'm an automotive mechanic, strong in electrical, and I'm struggling a little bit understanding this situation. Why was the engine being changed? Was the vehicle running on the old engine? What did the new engine come out of? Was it complete?

The vacuum harness connector is probably for the evaporative emissions system or the variable intake manifold solenoid controller. A 2-wire connector is rarely used on a sensor. I can't think of one on a RX. If you tell me the color of the wire & it's tracer I can look on my diagrams and see if I can tell you what it came from. Your charging issue is a separate issue. And ^^ Dave there is right; ALL your grounds must be connected before you start diagnosing issues like this.

The engine had a bad case of bottom end / rod knock. The engine that went in was complete and came with a harness but it was from an ‘05 Highlander and the connections under the glovebox were different so I used the harness original to the vehicle. The vehicle did run before I took the engine out but it did not sound good and I had 6 codes from the issue that have disappeared since. (Over Retarded cam timing banks 1 and 2, and 4 evaporative related codes p0430, 441, 446 & 455 which were all happening because the composition of emissions was being thrown out of whack due to irregular timing caused by the crankshaft going dry all those codes have since been cleared and did not reappear.

I am pretty sure the 2 wire connector that melted is indeed the variable intake manifold solenoid. It is part of the vacuum system and is attached to a metal rail that has 2 electrical connections in total as well as vacuum tubes and sits atop the front edge of the plenum. The melted connection is a rusty reddish brown color.
This is a picture of it


But I believe the camshaft position sensors on the RX also have 2 wire connections.

 

[Noltz]

Yeah you're absolutely right. This is an older design than what I typically see now and in fact most of the sensors are simple 2 wire. Wow. I thought Lexus would be using the newer 5v ref sensors sooner but I was wrong.

PM me your email address and I'm going to send you the entire wiring diagrams for your engine compartment. That should help you figure out what goes where by identifying the wire colors.

 

[LexusLover]

So I did a few things today. I took the service ports off the battery, emptied the acid and then flushed the cells with baking soda solution a few times. Tomorow I’ll fill them up with some Epsom salt water and see if my neighbor will let me borrow his charger since he offered.

Before that though I did test the battery which was just above 10v and I hooked the multi tool up to the negative terminal and negative harness which was showing a draw of a little more than 1000 milliamperes i pulled the fuses and that showed the problem is located in the ECUB and Dome light cluster and I’m guessing the dome light and sunroof are linked? Not 100% on that but either way that was what I came up with today. I was told not to do the test with a battery that wasn’t fully operational but after I recondition the battery I have I’ll run the test again. I did test each cell individually Hooked the negative terminal to the first cell which was around 1v then every other cell to cell connection was no more than a few hundredths over 2v but I also checked the voltage between the positive terminal and the last cell and that was around .9v

I’m not sure what it all means but I’ll do some more researching and as I said I’ll retry again with my reconditioned battery or a new battery if the reconditioning fails.

 

[Wrench97]

The car needs to sit for up to 1 hour before all the modules/networks and lighting timers go to sleep.
The old method of pulling fuses no longer works on modern cars.

 

[LexusLover]

The car needs to sit for up to 1 hour before all the modules/networks and lighting timers go to sleep.
The old method of pulling fuses no longer works on modern cars.

This is a 2004 Lexus rx330 it doesn’t have a blue tooth touch screen radio. Or push to start ignition. It’s pretty simple. Besides the automatic windshield wipers, automatic side view mirrors automatic curve following headlights, backseat DVD player and heated seats it’s nothing too fancy.
Are you saying that the ecu-b and dome light curcuits current draw could be caused by having the doors open and not shutting thungs and waiting an hour? That would be nice

 

[Wrench97]

ECUb is the Engine computer it will always have a small draw, the interior lights have a timer to keep them on when you close the door for a set amount of time.
Any car past the late 80's pretty much has computer control units and network interfaces that do not power off with the key.

 

[LexusLover]

ECUb is the Engine computer it will always have a small draw, the interior lights have a timer to keep them on when you close the door for a set amount of time.
Any car past the late 80's pretty much has computer control units and network interfaces that do not power off with the key.

So reading between the lines again

I should get a hood battery in (wether it be my reconditioned battery or a new one) make sure the doors are closed for an hour and the transponder key is far away from the vehicle and then test the ECU-b and Dome light circuits for draw?
But Isn’t 600 milliamperes a little heavy of a draw for a vehicle that is keyed off?

 

[Wrench97]

You have to measure voltage drop across the fuses, pulling a fuse and reinstalling will "wake" the module back up.

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