Toyota Camry Testing Knock Sensors Harness No Continuity

04-28-2020, 05:07 PM

Quote:

Originally Posted by Devbot View Post

I thought about this after the new ECU failed to fix it, but i dont have the first clue where these wires start and end up. How hard of a job is it?

That's a hard question to answer. I can rank it in terms of hardest jobs I have done, 1 through 10. 1 meaning an air filter replacement and 10 being complete engine swap and rebuild. I'd rate removing and re-installing an engine harness a 5, since it's for both the engine and the transmission. The engine part actually isn't that bad, since you can leave the lower engine harness in place (alternator, starter) and only replace the main harness. You can disconnect the ECU and just shove the whole harness into the engine bay and just go one by one following wires and taking them off. No two connectors are alike so you can't mess it up. You do have to pull the upper intake to disconnect the fuel injectors. The auto transmission is what will give you the most trouble since there's no space between the transmission and the floorpan to disconnect those connectors and they corrode something fierce. I had to use mirrors and pliers on mine.

You'd also have to find a harness from your year and drivetrain. So a 98 4WD isn't the same as a 98 2WD, which isn't the same as a 99 2WD, etc.

04-28-2020, 09:28 PM

Thanks for the info, sounds like quite a bit of work and money. Considering I've dumped a lot of cash into this already I'm gonna continue to keep prodding around first and hope I can catch a short in progress. From the knock sensor connector to the ECU initially measured less than 0.2ohms, maybe I just need to try over and over

Edit: forget to mention that the car now idles better (only high on a cold start) and OBD shows no retarded spark despite the codes, so that's a plus

04-29-2020, 11:00 PM

A short may not affect continuity to the ECU but it may still affect the signal. If a rat chewed the wires so that the signal and grounded shielding wires are touching but the signal wires are still intact, you would get continuity to the ECu, but also continuity to ground. Depending on the resistance in the ECu circuit, it is likely that more current will got straight to ground, which could potentially throw your ECU for a loop and trigger a code.

Continuity tests should be done after depinning the wires from the connector, do a search and you'l see how to do it, or at least unplugged from ECU. It isn't a good idea to test for continuity while connected to sensitive electronics as the voltage used to test can damage components.

05-03-2020, 01:19 AM

car-part.com

Might do better searching for other parts besides harness on year you need and then calling to see if they'll pull or you can pull yourself. I know from experience that wiring harnesses aren't a big mover so they might have the truck you need on the yard but not bothered to list the wiring harness

edit: although I'd still start with just rewiring the couple wires you suspect are shot, of tracking down the flaw in your existing harness, whole replacement is a PITA, much easier to cut and splice what you need

05-03-2020, 07:42 AM

Quote:

Originally Posted by Devbot View Post

Where would be the best place to find a spare ECU harness? Pick n pull shows no 4runners anywhere close

PM fellow member

@DeathCougar

. He is in the Evergreen state as well.

05-05-2020, 07:51 PM

Quote:

Originally Posted by jbtvt View Post

although I'd still start with just rewiring the couple wires you suspect are shot, of tracking down the flaw in your existing harness, whole replacement is a PITA, much easier to cut and splice what you need

That's more or less what I'm starting to get at - from what I understand they have to come from a nearly identical vehicle and trying to find a harness for a Californicated '00 SR5 4x4 specifically could take a while. Local hardware store sells lots of shielded wire I could use to replace what's there but I'm still figuring out how to properly fix them to the connectors.
The other problem is determining which wire is giving me hell; given that it's been quite a few codes (0135, 0325, 0330, 0420; knock and O2 sensors) then it seems like it's unlikely to be purely the knock sensor wire, and I feel like the combination of codes has to help allude to this. At least that's my take. I'm clearly no electrician.
Thanks for the help everybody, btw. Much appreciated. Just my damn luck that 99% of threads on this issue either come to a halt or end with "took it to the shop lol"

05-05-2020, 10:41 PM

Quote:

Originally Posted by Devbot View Post

Just my damn luck that 99% of threads on this issue either come to a halt or end with "took it to the shop lol"

"be the change" ;)

Shielded wire is basically a coaxial cable. Just tie a length of regular wire into the shielding/sheathing wires, I'd use solder but might be able to get away with a crimp connector as long as you check connections, wrap other end of wire around a tec screw anywhere on body and shoot it in. Main conductor connects like any other. Heat shrink and/or 2 coats liquid electrical tape to insulate

Thinking, it's interesting that all the codes you mention are related to a fluctuating/oscillating voltage signal to ECU. I wonder what the signals are compared to internally. Maybe there's some error in the reference signal for either volts or...time signal (is hz even a thing in dc?) Have you checked how many volts your regulator I putting out?

05-17-2020, 09:20 PM

Fixed the hood release. Hopefully it'll last another 20 years
What are the chances of finding one of these connectors, outside of buying an entire engine harness? Roped in my pops to help me and he had the same idea about splicing in some new connectors and running it to the ECU, if they're easily found that is
Hopefully this will be the last step; really want to put this behind me so I can get to building this into a crawler

06-20-2020, 01:06 PM

Been a week and I feel comfortable in saying;
the gremlin has been caught

In the end I'm not sure what exactly remedied the issue. I did read iffy things about Matsu's knock sensors, and Denso's seem to test out much more cleanly, so if there's anything to be taken away - use OEM Denso sensors

Thanks for everybody's help.

04-28-2020, 05:07 PM	#31

Elite Member	Quote: Originally Posted by Devbot I thought about this after the new ECU failed to fix it, but i dont have the first clue where these wires start and end up. How hard of a job is it? That's a hard question to answer. I can rank it in terms of hardest jobs I have done, 1 through 10. 1 meaning an air filter replacement and 10 being complete engine swap and rebuild. I'd rate removing and re-installing an engine harness a 5, since it's for both the engine and the transmission. The engine part actually isn't that bad, since you can leave the lower engine harness in place (alternator, starter) and only replace the main harness. You can disconnect the ECU and just shove the whole harness into the engine bay and just go one by one following wires and taking them off. No two connectors are alike so you can't mess it up. You do have to pull the upper intake to disconnect the fuel injectors. The auto transmission is what will give you the most trouble since there's no space between the transmission and the floorpan to disconnect those connectors and they corrode something fierce. I had to use mirrors and pliers on mine. You'd also have to find a harness from your year and drivetrain. So a 98 4WD isn't the same as a 98 2WD, which isn't the same as a 99 2WD, etc.
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Toyota Camry Testing Knock Sensors Harness No Continuity

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