Emissions tests keep resetting to not ready status...

[Majindan]

So I had a similar issue same time last year due to a P0420 CEL, replacing the trash Bosch O2 sensor with a Denso and ended up pulling the negative battery terminal for a few hours and all tests cleared same day, emissions passed. Now, same issue but the negative battery pull isn't working as test showed as ready once, and now all of them were reset for no apparent reason.

Previous thread here: http://www.toyota-4runner.org/3rd-gen-t4rs/226400-please-help-before-i-drive-thing-into-lake.html

Using Torque Pro, I did clear a P0440 CEL a few months ago with no further issues. I know clearing codes with Torque can cause issues with the emissions tests which is why I already pulled battery terminal to fully reset the ECU along with leaving the headlights on to make sure all power was purged.

I bought a brand new green top Interstate battery this time last year and terminals/posts are very clean with protectant on them. On a side note, when I turn my truck on, my JVC headunit will be on factory default static radio station but all my saved data such as station memory and audio settings are in place and every now and again it will kind of lock up and reboot. I've noticed too that even after letting the truck sit with no battery for four hours the radio had kept all my settings which struck me as odd.

Should I be checking all my ground wires on the truck or could the radio wiring be causing just enough of a hiccup to reset the ECU emissions tests?

You guys know more about 4Runners than anyone I know and I have to get emissions clear ASAP.

Thanks!

 

[tarsun]

so the issue is that your car is not passing the readiness monitor tests?

 

[Majindan]

so the issue is that your car is not passing the readiness monitor tests?

They all showed as complete Friday minus the catalyst test...started the truck up last night, they were all reset.

Could be worth mentioning my truck long term trim has been peaking at 17-18% per Torque, but no noticeable difference via driving or fuel consumption.

 

[octanejunkie]

Typically, for all tests to be performed either after clearing codes or a full ECU reset, the vehicle has to drive about 150-200 miles (in my experience) before all tests report. Bringing the car in before all tests have reported is usually an automatic fail, at least in California.

A parts store code reader usually shows test status (flashing means not ready) as well as pending codes and present codes. I've had an OBDII reader for years but use it only on occasion. I've not had my 4 runner throw a code since getting Torque Pro so I can't comment on what it shows regarding readiness.

 

[Majindan]

Typically, for all tests to be performed either after clearing codes or a full ECU reset, the vehicle has to drive about 150-200 miles (in my experience) before all tests report. Bringing the car in before all tests have reported is usually an automatic fail, at least in California.

A parts store code reader usually shows test status (flashing means not ready) as well as pending codes and present codes. I've had an OBDII reader for years but use it only on occasion. I've not had my 4 runner throw a code since getting Torque Pro so I can't comment on what it shows regarding readiness.

I have the readiness PDF from the Toyota shop manual so it's not really mileage but the conditions required to complete the tests, which I've done. Just doesn't make sense why they show complete then reset, as if the ECU is losing the testing data after I restart the truck. Torque Pro does the same thing as an autozone OBD reader and I have a reputable bluetooth OBD device.

 

[Buckaroo]

I think you are on the right track with the discussion on the battery & grounds. Sounds like you are momentarily losing charge to the ECU & monitors are all resetting. Suggest you have battery & alternator tested at Advance Auto, etc - perhaps intermittent short in battery. Also remove, clean and re-attach ground wire on inside fender wall. You say battery terminals are clean and leads are firmly attached which is good. Make sure top of battery is clean as well - if dirty use baking soda solution.

Buckaroo

 

[sakoluvr]

Is this the same battery from your original thread that you linked to?

 

[fourfive]

I've been running into this issue every year for the last few years. After fixing the necessary stuff to address to my cel codes I would take it through the drive cycles until my obdii showed it was ready but either after driving for a while or shutting down/restarting the engine it would show not ready again. There's no pending codes just states not ready. My assumption is that things are getting old and are on their way out (such as cat, exhaust, evap stuff).

 

[Majindan]

I think you are on the right track with the discussion on the battery & grounds. Sounds like you are momentarily losing charge to the ECU & monitors are all resetting. Suggest you have battery & alternator tested at Advance Auto, etc - perhaps intermittent short in battery. Also remove, clean and re-attach ground wire on inside fender wall. You say battery terminals are clean and leads are firmly attached which is good. Make sure top of battery is clean as well - if dirty use baking soda solution.

Buckaroo

Does anyone have a PDF showing where those battery grounds are by chance? I can run to O'Reily at 1 today eastern time for the battery/alternator test. Yes, it's the Interstate Mega_Tron II green top battery I bought almost exactly a year ago.

edit; What sensor or readings could I possibly look at in Torque that would show me if alternator or battery is not holding correct voltages? Not sure of the range they need to be in either.

 

[Buckaroo]

Does anyone have a PDF showing where those battery grounds are by chance? I can run to O'Reily at 1 today eastern time for the battery/alternator test. Yes, it's the Interstate Mega_Tron II green top battery I bought almost exactly a year ago.

edit; What sensor or readings could I possibly look at in Torque that would show me if alternator or battery is not holding correct voltages? Not sure of the range they need to be in either.

I quickly looked for a ground wire diagram but didn't find it - help from others? The important thing is that you have a good ground from the battery to the frame and from the frame to the ECU. Fully charged battery should read 12.6V with engine off. Engine running across the terminals should be more - maybe 14 - 14.5V.

If possible, test voltage drop across each of the grounds with engine running before you take them apart to help isolate the issue.

Buckaroo

 

[Majindan]

I quickly looked for a ground wire diagram but didn't find it - help from others? The important thing is that you have a good ground from the battery to the frame and from the frame to the ECU. Fully charged battery should read 12.6V with engine off. Engine running across the terminals should be more - maybe 14 - 14.5V.

If possible, test voltage drop across each of the grounds with engine running before you take them apart to help isolate the issue.

Buckaroo

Thanks for the help, I'll definitely be taking the truck to O'Reily as I don't think my multimeter is in my recovery box.

 

[RonJR]

Your radio is your clue. If it is resetting to a default station, that suggests the power is being interrupted somewhere. The station presets are probably stored in EEPROM, which doesn't reset when power is interrupted, so you wouldn't notice anything there.

You need to find the intermittent connection in your power wiring. Since you haven't had any sudden shutdowns on the highway, it's probably between your battery and your alternator, such that during driving your alternator keeps things alive even if your battery momentarily goes offline. Most likely it's the smaller of the wires that connects to the +terminal of the battery (not the big cable, which goes to the starter.)

 

[Majindan]

Your radio is your clue. If it is resetting to a default station, that suggests the power is being interrupted somewhere. The station presets are probably stored in EEPROM, which doesn't reset when power is interrupted, so you wouldn't notice anything there.

You need to find the intermittent connection in your power wiring. Since you haven't had any sudden shutdowns on the highway, it's probably between your battery and your alternator, such that during driving your alternator keeps things alive even if your battery momentarily goes offline. Most likely it's the smaller of the wires that connects to the +terminal of the battery (not the big cable, which goes to the starter.)

I knew the radio had to be a big clue. So follow the wiring from the alternator to the positive battery post right? Checking for cracks and tightness/corrosion of whats holding wire connected?

 

[RonJR]

I knew the radio had to be a big clue. So follow the wiring from the alternator to the positive battery post right? Checking for cracks and tightness/corrosion of whats holding wire connected?

That's where I'd start. Turn the key to ACC, turn on the radio, and listen to it or have someone watch it while you wiggle the heck out of the various wires and connections in that area. If there's an intermittent you should notice it pretty quick.

 

[Buckaroo]

I knew the radio had to be a big clue. So follow the wiring from the alternator to the positive battery post right? Checking for cracks and tightness/corrosion of whats holding wire connected?

The visual inspection is good but, if you had that multimeter, you would want to check DC Volts from the alternator terminal to the + Battery terminal with the engine running. You should get 0 - ~0.2 volts drop. Wiggle it to see if it the voltage jumps around (should not). If you see something like 1+ volts, look for a loose connection and, if you don't see anything, replace that wire.

Buckaroo

 

[octanejunkie]

There are two wires to the fusebox in the engine bay, one from the bat and one from the alt - check for voltage and continuity on those - if you don't have a multimeter you can use a light tester off of ground to establish basic yes/no. It's very possible your fulltime hot connection is compromised.

 

[Majindan]

"Fully charged battery should read 12.6V with engine off. Engine running across the terminals should be more - maybe 14 - 14.5V."

Had my multimeter and my results were dead on the above. Guess I'll be checking the other grounds when I get home later tonight. The short fender negative right by the battery is perfect as I had just recently replaced the connector and cleaned all that up when I put my KC lights in.

 

[Majindan]

There are two wires to the fusebox in the engine bay, one from the bat and one from the alt - check for voltage and continuity on those - if you don't have a multimeter you can use a light tester off of ground to establish basic yes/no. It's very possible your fulltime hot connection is compromised.

Do you have any visual aids to help with that? I'm still learning and I've never had electrical issues. Thanks all for the feedback thus far.

 

[TheDurk]

I'd try this. Put headlights on high, engine off. Point at a wall or something. Then go pushing and pulling on all the battery positive and ground cables and see if anything gives a jolt to the lights. That should give you a clue, if it happens. No guarantees, but worth a try.

Also verify the ground by the diagnostic terminal plug on the engine (aka sensor ground) and get it good and tight.

 

[octanejunkie]

Do you have any visual aids to help with that? I'm still learning and I've never had electrical issues. Thanks all for the feedback thus far.

See the pic attached from my '99 fusebox, right hand side close up: the stud on the top right comes from the alt while the bolt head visible towards the bottom comes from the battery.