Electrical Problems

Hello, I'm hoping someone can help me because I am at a lost.
2002 Tundra 4.7 Automatic,no aftermarket alarms

-My tester shows a Groups of fuses grounding out in the engine bay and some inside (see picture).
-OBD2 reader not dispaying. Connector has no power. See picture
-Engine won't start, relay clicks. Battery has been tested at autozone.
-when Key is in ACC a humming is coming from engine bay, possible starter which is under manifold

Any suggestions where to start? Am I correct in that the Fuses should NOT be reading gounded?

 

I'd love to hear @BubbaW input on this just because he's a master at finding what's upstream that could take out groups. Wiring whisperer.

That said, I want to direct you to THIS THREAD. Specifically, know about this common issue in the bolded red text from this bullet point in that thread.

• These trucks usually don't have a ton of other electrical issues. Hidden corrosion inside the battery/alt cables happens. Sometimes, a couple thousand miles after timing belt changes, people will have startup issues because the crank position sensor wasn't properly tucked away and gets rubbed by a belt (pic), correct routing info here. There's also a similar problem with camshaft position sensor under the cam cover, where the belt will rub through (pics). There's the rodent issues mentioned earlier. Occasionally, water leaks can send water down into the ECM behind the glovebox (pics), or into the fusebox inside the cab/dash (pics & pics & pics, it happens a LOT). Many drain/vampire issues trace back to aftermarket add-ons whether the owner knows they exist or not - alarms as mentioned earlier, brake controllers, poorly installed trailer receptacles, those are some big ones.

I'm not saying that's your issue. But as you will see from the "pics" links, water leaks - especially if you're the kind of person who doesn't fix cracks in your windshield, or you had the windshield poorly replaced, or you've got rot around the windshield seal, or leaks happening at the A-pillar - it is very common for water to hop onto the wire harneses below the windshield/coming out of the A-pillar, those harnesses that come into the back of the fusebox are a direct pipeline to carry water down into the fusebox.

If it turns out this isn't something simple, like one of the engine bay fuses being popped and not feeding power to an interior circuit, I would be highly motivated to click those 'pics' links and see if you find similar in your truck. It's happened to more than a handful of people on here, some people more than once.

 

What work, if any, were you doing that caused you to make these checks or did it just happen out of the blue ?

Pins 4 and 5 of OBD port are both normal ground points. Pin 16 is 12vdc always and is protected by a 7.5A fuse in Eng bay.

There should not be voltage at starter to make noise when in ACC position, only when key is turned to Start pos(cranking) BUT there is voltage at Throttle control motor when in ACC....IIRC. I don't have 02 to check. Could that be the noise you're hearing ?

On the engine bay fuses, is that check made with or without fuses in place ? I'm actually not sure how you're making that judgement, so hard to say what if anything that means. Can you explain how you determined that ?

 

@rstill718 answers to my questions from above....

Tundra would not start so replaced battery. After a week this battery would not start truck. Prior the truck check engine light was on... Hence why I tried odbc meter which I have used before on the truck.
The truck was fine and everything worked including cruise control, lights, interior, power door & windows untill the it wouldnt start one day.

I've check all fuses. Removel of fuses and testing terminial is how I found the ground, sometimes both sides were reading ground. I also checked the inside fuse box and some teminials were grounded with the fuses out.

Maybe the TCM but I can also here what sounds like the starter spinning AFTER you switch back to OFF. This has been happening for a long time.

I removed all 4 10amp fuses and then checked each terminial that the fuse inserts into and at least one side read as a ground.

 

As @shifty` mentioned, water intrusion whether driver side or passenger can cause total havoc, either on the ECU/pass side or Integration Relay panel/driver side( attached to backside of cabin fuse panel.)

On these ground measurements, are you doing this with an actual volt/ohm meter or a circuit tester ?

I’m not discounting these ground readings but unless I was the one making the measurements at certain points, I can’t agree that is a problem.

My suggestion is to put all fuses back in, making sure visually they look good, then let’s start from there. With the understanding certain checks at a fuse might show ground according to which one and right conditions. Example can be given if need be.

Digging into checking the Integration relay panel is not an easy task but may be necessary according to what you find.

 

My apoligies as I just can't get Chrome to reply using Quotes or more likely it is user error.

On these ground measurements, are you doing this with an actual volt/ohm meter or a circuit tester ?
BubbaW I used a meter from Harber freight that clips on both post of the battey
I’m not discounting these ground readings
BubbaW You should because I have no clue what I am doing

As mentioned in the suggestions by you guys, there is a #$@! Leak right above all the wires in the Driver side Fuse Box. I am not sure if this is why it won't start but this seems the most logical place to begin.

Photo for reference: There is a liner and when I stuck my finger in there and it was wet. I also heard a light buzz and jiggled the wires and it stopped. I will take pics during process so I know how it goes back together if anyone needs them for 2002 Tundra.

 

We love pics and when you go digging, be sure to undo battery so you don't let all the smoke out. Good Luck....

If you haven't looked at any of the links shift posted, the below example is what you might find.

 

Yup, pro tip: Sharpie marker to any relays before you pull them so tou know the order and they go back into the right spot. If you see green anywhere, it’s bad news. Be careful about what you replace it with, part numbers varied even in the same years. If you need help finding the right part, shoot me your VIN and I’ll see if I can pull it in the EPC.

 

Update for 2002 Tundra 4.7 Automatic, S5:
Problems: won't start, no power to OBD,leak found above cabin fuse box.

I pulled the fuse box out and could not find any damage, see pictures. Is it possible a bad starter could cause this? The starter is under intake manifold.

 

You check the passenger side where the ECM is? Any leaks there?

 

Oki Doki....pardon me if I'm too basic.

Have you verified with the Etekcity VOM(volt/ohm meter) that you do or don't have voltage at the OBD connector....using pin 4 or 5 as gnd(black lead of meter) and pin 16 pos(red lead of meter), turn knob to DC highlighted in red below. Also have you double checked the 7.5A OBD fuse in Engine bay. If it's indeed good, remove fuse, place blk meter lead on neg of battery and with red lead, do you have 12vdc on either terminal where the fuse goes ? Trying to fix OBD might help if it has a code that might help determine no start/no crank condition.



BTW, have you or anyone recently did any work like changing timing belt or around the cam or crank position sensors.

I ask that because....

 

Update: Lots of rain here plus my truck has been parked uphill which is rare. Traced water trail as seen in pictures. I know I will get reprimanded but could I just splice the wire? You know the big no-no.
I rewired and the Control module now has power but still no crank.

 

Yes. I have now power to the OBD after wire repair.

 

Sorry to hear you were another victim of water intrusion. I always hate to see this. Glad to see you could get it fixed though.

 

Agree with shifty and when the weather permits and have the time, I would suggest taking a good look at all those connections, as difficult as it seems. Also, a blow drier when wx permits would help.
If you noticed any moisture on passengers side, I'd check behind the glove box area in particular the ECM as @KNABORES suggested.

If that connector you're showing was located up behind fuse panel drivers kick panel area, that is the IA4 26 pin connector that contains pins for BATT(12vdc red wire/pin 1) input control signal to ECM, Starter relay(pink wire/pin 24), C/OPN relay(yel wire/pin 26), OBD(yel wire/pin 22) etc, just to name a few very important items.

I would not bother troubleshooting till connectors are cleaned up, wire spliced back in and moisture dried from all connectors. If this had set too long, I bet the fuse/integration panel would of had a more visible corrosion look than what you found.

BTW, did you notice any moisture inside the fuse/integration panel when you took it apart ?

 

Bubba there was no mosture in the fuse box. Some moisture was on the outside of wire harness but none inside connectors except on the one you pointed out, IA4.
I've printed this stuff out and will check the wiring further as suggested.
Thanks to all

 

Update: The OBD2 connection and weird buzzing in cab has been resolved by repairing wire and cleaning as suggested above. I cleaned and checked the wires underneath.

The starting issue appears to be the starter itself. My son turned the key as I tapped the starter with an extension and after several strikes it started. I warmed up the engine sinced it has been sitting a while. Last try it started but after sitting overnight I doubt it will from past experience.

Q: Could it be anything besides starter?
Q: Brand suggestions since the one in the truck is not an OEM.
Shifty had this link in another post:
https://www.rockauto.com/en/moreinfo.php?pk=1292798&cc=1357938&pt=4152

Q: Has anyone supplied pics doing the under the manifold starter install?
@BubbaW you indicated " in ACC position, only when key is turned to Start pos(cranking) BUT there is voltage at Throttle control motor when in ACC....IIRC....." Q: Is it normal to smell gas from the "Throttle control motor assembly" even when the truck will not start?




I used a long rod to tap on the starter going through the hole marked.