Obd won't connect to ECU.

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hagnecco

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I have a cheapy bluetooth obd2 connector off of Amazon. I was using it no problem to read my 4runner, camry and Ford F250. After I decided to do the water pump, timing belt, idlers, valve cover gaskets, spark plug wires and spark plugs it decided to not let my obd connect to the ECU.

I've checked and verified it still works in the other 2 vehicles.

I use the Torque Pro app on my Samsung S7 which tells me it is connected via Bluetooth to the OBD reader, but does not have a connection to the ECU.

Where is a good starting point to check the connection between the OBD port and the ECU? Also, I see under the hood is a diagnostic port similar to the OBD port. What is the purpose of that and can it help me with this?

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Might check fuses for ECU related circuits? Just a hunch.

It's obviously getting power to the port if the BT adapter even powers up, so I don't know how relevant that would be.
 
I know you tried it in other cars but I don't trust those adapters. I'm on my third one and they seem to develop weird fails, including allergies to specific cars. My last one before this did the same thing on the 4Runner but read my son's BMW--go figure. Try a wired reader. Autozone and others will loan you one for free to use in the parking lot.

Below is the wiring diagram for Engine Control for the V6 on your '97. The OBD connector is on p. 75. Apparently only four of those pins were used--two grounds, the power from the fuse, and a single shielded white wire from the ECM. I think you are up to the task of checking those. Don't forget to verify the shield has ground.

But try a different reader.
 

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hagnecco said:
I have a cheapy bluetooth obd2 connector off of Amazon. I was using it no problem to read my 4runner, camry and Ford F250. After I decided to do the water pump, timing belt, idlers, valve cover gaskets, spark plug wires and spark plugs it decided to not let my obd connect to the ECU.

I've checked and verified it still works in the other 2 vehicles.

I use the Torque Pro app on my Samsung S7 which tells me it is connected via Bluetooth to the OBD reader, but does not have a connection to the ECU.

Where is a good starting point to check the connection between the OBD port and the ECU? Also, I see under the hood is a diagnostic port similar to the OBD port. What is the purpose of that and can it help me with this?

Sent from my SM-G930U using Tapatalk
Click to expand...

I had one too, it is a cheapy for a reason, uh huh.
 
TheDurk said:
I know you tried it in other cars but I don't trust those adapters. I'm on my third one and they seem to develop weird fails, including allergies to specific cars. My last one before this did the same thing on the 4Runner but read my son's BMW--go figure. Try a wired reader. Autozone and others will loan you one for free to use in the parking lot.

Below is the wiring diagram for Engine Control for the V6 on your '97. The OBD connector is on p. 75. Apparently only four of those pins were used--two grounds, the power from the fuse, and a single shielded white wire from the ECM. I think you are up to the task of checking those. Don't forget to verify the shield has ground.

But try a different reader.
Click to expand...

Where do you get these schematics? I'd like to get the whole book so I can stop buggin you guys! :)
 
TheDurk said:
But try a different reader.
Click to expand...

I also have the ScanTool OBDLink MX. Tried that one with the same results. Works in the others, but not the 4runner. Truck is getting new brakes all the way around. I'll start with the testing by the end of the week. Thanks for the schematics. What a HUGE help!
 
hagnecco said:
I'm not familiar with how to use it. Isn't it just contacts for testing with leads?

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Click to expand...



I tested my abs through that port a few years ago. Jumped two pins together and counted flashing abs light.


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Did you ever figure anything out with this? I currently am having the same issue after dropping a new motor and trans in my 99. I have power at the (16)BAT pin and grounds at both the (5)SG and (4)CG pins. Wired scantool powers up once hooked up but keeps saying connection error try again. It works on every other vehicle I have tried.
 
ELM327 v1.3a Version F

No diffinitive answer, but still working it. I've checked and rechecked the vehicle and determined there is nothing wrong with it. 2 out of 3 of my Bluetooth OBD readers don't work with the 4Runner, but checking other vehicles, they all work.

To communicate with the OBD, there are several different protocols used today. These protocols determine how to communicate. This link gives a good breakdown: OnBoardDiagnostics.com - OBD-II Network Standards

Our 4Runners use J1850 VPW (at least my '97 does). I've concluded I'm able to communicate using every other protocol in other vehicles, but cannot with the 4Runner because there is an issue with the J1850 VPW protocol within these readers. My Ford recently developed thus same communication error which uses J1850 PWM. Because the protocols are wired similarly, there's either a power or ground issue internally causing these readers to fail in due time.

Scantool has a forum where you can post the details of your issue and they can determine whether to warranty your product or not. I'm still awaiting their answer.

If there are any confident or willing electricians, I think I may have found a solution however, I'm not willing to open my products. The link below was posted from 2010, so I have not verified how well this works. But it mentions using two 100 Ohm resistors and a 560 pF capacitor versus a single 120 Ohm resistors and no capacitor.

FAULTY ELM 327 INTERFACES DE-MYSTIFIED (READ HERE) - Multiecuscan

For reference, I attached the ELM327 v1.3a Version F Data Sheet straight from ELM Electronics website: https://www.elmelectronics.com/products/dsheets/
See Page 56 for the full wiring diagram. There are other data sheets, but I selected v1.3a because my OBD Link is identifying itself as a v1.3a.

If anyone is willing to try this and report back, maybe we have a fix.
 

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I would also check the grounds esp the one on the engine near the engine obd port. Its a closed circuit, the grounds are equally as important as the feed.
 
Port is good, I've check and rechecked. I have ground at wires 4 and 5. And I have 12.6v at wire 16. If the port is bad, it's not possible I can consistently connect to a known good OBD Reader and consistently not read the other 2. The other 2 are capable of reading my 2002 Camry which uses a different protocol to communicate.

Grounds are good. I recently had a charging issue, so I cleaned up all grounds and checked for resistance. I did recheck that same engine ground with the ground at the OBD and have continuity, with minimal resistance.

Scantool has determined their product to be faulty in not connecting to vehicles with J1850 VPW protocols. They are shipping me another under warranty. I can connect to other vehicles which do not use that protocol.

The other Bluetooth OBD that did not work was my cheap Chinese import off Amazon. This is why I posted the link above. Chinese imports seem to have been incorrectly wired.

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Can't help with this issue, but wanted to add I've had an ELM 327 bluetooth reader for many years, and it works flawlessly in my 2002 4 runner via bluetooth. It's worked in every car I've had actually, including a 98 BMW M3, 2008 tundra, and 2000 maxima. They are great little cheap tools. I think I paid around 10 bucks for mine years ago.
 
Just jumping on this for the future as someone experiencing the same issue. My understanding is that the 96-97 models use the VPW protocol mentioned by OP, but future models updates the protocol. Interesting that there are issues on several.devices reading that protocol.

Have a different reader arriving on Friday and will update with progress.
 
Any update on how the new reader is working? I use a OBD/USB reader plugged into a chinesium Android head unit running Torque. Worked fine for a while then just quit. Seems to be a similar problem to this thread

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Sorry to hitch my wagon to this thread, but now that we are in 2020, can anyone recommend a scanner that will work without issues on my 2000? I have zero experience with these devices and apps but I have a crappy old iPhone 8+ Are there any that even work with iOS? i've got a current Macbook running Win10 if that will work w/BT.

EDIT - Nevermind - I got up to speed on the tech. Open to specific device endorsements, though.

Thank you!
 
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