P1500 Code After 400 Watt Anytime Mod

Posted in this thread as well:
https://www.tacomaworld.com/threads/how-to-ac-outlet-in-cab-400-watt-anytime-mod-2nd-gen.322320/


Mod works great but got a P1500 code. Cleared it once and it came back on after using the inverter for a day.

I'm charging a goal zero yeti out of the bed outlet with a 300W power supply.

The goal zero is reading ~300W input so everything seems to be working with the inverter. 400W light is on, on the switch.

Just keep getting this dang DTC. Please help!



Apparently it's due to an idle-up signal from the inverter, for over 10 seconds.
This link is seems helpful:
https://zinref.ru/avtomobili/Toyota/211_Toyota_FJCruiser_GSJ 10_15_series_2007_english_copia/082.htm

 

You may disconnect the idle up signal to prevent this from occurring. This is a side effect of doing the mod if you are drawing high currents for an extended period of time. Your inverter no longer know the vehicle speed so it will try to idle up even if it doesn’t have to because you are driving it

 

I briefly looked at the system workings.
I too thought of disconnecting the idle signal wire. But thought that would prevent the idle up when needed. Like when parked. So, I didn’t want to potentially cause someone else a “problem”. I seriously doubt it would really hurt the truck, alternator, or cause any problems.

I honestly didn’t put a lot of effort in to figuring out a fix. Mostly because I think the Stock Inverter is useless, and not worth spend a lot of time or money on.
( No offense OP)

If it were me, I’d go with a whole new inverter.

 

I'm not sure how much RPM it actually idles up, but my thoughts are that the difference is negligible. If you wanted to get fancy (assuming you have automatic), you can interrupt the idle up circuit with the transmission sensor as alternate means of knowing it is "stopped". For example, the ELS signal would only get to the ECU in park or neutral.

 

I don't want to relocate and rewire a new inverter so I'm fine removing the idle-up signal.

I have the wiring diagram attached. Do I just cut the black and white wire?
Does the idle up signal send voltage to the ECM?
Will there be an issue with either the ECM or inverter with an open circuit?

 

Disconnect the Black wire with white stripe from V8 terminal 9. Cap the end coming out of inverter to prevent any shorts.


There is also an electric load signal to idle up sent by the tail light fuse, so your truck will still "idle up" if you leave the parking lights on the same as if the inverter was running as well as while the A/C is on.

 

Awesome. Great information as usual.
I wish I could figure stuff out as easy as you guys.

I’m still in the stages of , - Try it. If it doesn’t work, it’s still a success if I didn’t manage to break something else while trying it.

 

Hmm going to have to test this when I get home. Curious how much it actually idles up? Never heard of that.

 

it will only idle up if drawing above the 8.3 amps.

 

So I tried this last night with a small vacuum. Truck was up to temp and idling. Turned the inverter on and then turned the vacuum on. No difference in RPM. If anything it dropped just a bit, which makes sense with the extra load.

Wonder if there are additional criteria before it will idle up, or if the Tacoma 1GR-FEs dont have that feature?

 

how many amps did it draw?

 

Plugged it into my Kill-A-Watt in the house and saw ~435 watts. So in theory thats about 30A on the DC side in the truck

 

Update on this fix. Disconnected the idle-up signal. Cleared the code and it didn't come back.
Drove around all weekend using the inverter. It was mostly working except the inverter would turn off when idling.
This includes when I'm in drive and stopped at a stoplight or traffic.

Pretty annoying but I just kept turning it back on and it was working fine.

This is probably the best I'm going to get with this mod but anyone have some crafty ideas?

 

Besides ditching the OE Inverter, no.
But, then again. I hold a grudge against the OE inverter. It did not run my circular saw. So I spent $350 on a battery powered. Haven’t even opened the outlet cover on mine in 5 or 6 years. Lol

99% of the time. My tail gate is a work bench. It also serves as a saw horse too.

 

it may be looking for a sensed load from the PCM when it outputs the idle up voltage. You could put a CLR in there and allow the idle up output to have a load on the terminal. I’ve never seen a detailed schematic for how the inverter itself works inside for the speed and idle up logic so this is just a best guess it might fix your issue.

 

I believe the idle-up signal stabilizes your idle, so no difference in RPM means its working correctly.
A drop in RPM means there is a load on your engine and no idle-up signal.

I was never able to run a vacuum on my inverter anyways. Already tried to clean my car that way...
It would turn on but every time I tried to use it on carpet, there would be a power surge past 400W and the inverter would turn off.

Not sure how you can run a vacuum over 400W with the stock inverter

 

If you modify the vacuum with a larger starting capacitor it might survive the inrush from the motor start. The stock inverter is pretty worthless IMO, so even the 400w anytime mod it’s just putting lipstick on a pig.

 

I was surprised it would power it as well. I guess theres probably just a bit of overhead in the '400W' rating they give.

Also, what you say makes sense. Simply maintaining the idle, aka not really an "idle up" in the old fashioned sense.