Code P1126, but no "limp home" mode. (2 Viewers)

[trudd]

New to me 2000 LC, 126k. Purchased 5 weeks ago. On our way out of a nearby state park yesterday, I noticed the CEL, VSC OFF and VSC TRAC lights on. I opened OBD Fusion app (iPhone - have a LE Link OBD-II reader installed) and pulled up code P1126 - magnetic clutch circuit malfunction. There were no other accompanying codes. I did a little research and decided to reset the codes to see if they popped back up. We drove another ~30 miles around town and performance was fine. No rough idle, no acceleration problems. It handled highway and city driving just fine. No previous mention of P1126 in the extensive dealer records from PO.

24 hours later, CEL and the two VSC lights came on again on startup. Again, no performance issues.

There are many informative threads involing TB, TPS & APPS, but the fact that I have no performance loss has me a little stumped. Seems most others had some kind of accompanying codes.

details
- running 87 octane since i purchased 5 weeks ago. could this cause build up in throttle body? i'm assuming PO ran premium.
- exhaust manifold very likely cracked. not sure which side. distinct ticking for the first ~3 minutes until car warms up. occasional ticking heard in city driving.
- occasional drips on passenger side floorboard. i need to check AC drain & evap. had to recharge recently and things settled in between 35-40 psi.

I'll be taking it to Edwin's shop (@green grass hopper ) soon for a base line. Guess I'll have to add this to the list if no simple solution pops up.

 

[trudd]

 

[Julian Stead]

Try cleaning the throttle body..

 

[trudd]

Cleaned throttle body, MAF, and put in a new air filter. Started her back up and got the code for APPS (P1120). Today I learned what Limp mode is. I couldn't get the code to clear from my app and didn't bother unplugging the ECU to let it reset. Just gonna nip it in the bud.

Looks like I'll be ordering a new APPS and following the well-known guide: An illustrated guide to replacing your APPS - Part 1

 

[trudd]

Little update, the P1120 was solved be re-seating the connector. Rookie mistake after poking around. No more limp.

Still got an intermittent P1126 code, so I replaced the APPS. Code went away for ~100 miles. It's been back again, intermittently, for the past two weeks. I haven't replaced the TPS yet, may get to that this weekend.

The CEL has only ever come on at startup, never while driving. Even then, I'm still not going into limp mode.

We'll see if TPS solves it. If not, what's the next solution? Replacing throttle body?

Also, I have a used APPS laying around if anybody wants a spare. Left the new one installed even though the old one isn't the culprit.

 

[daletron]

Little update, the P1120 was solved be re-seating the connector. Rookie mistake after poking around. No more limp.

Still got an intermittent P1126 code, so I replaced the APPS. Code went away for ~100 miles. It's been back again, intermittently, for the past two weeks. I haven't replaced the TPS yet, may get to that this weekend.

The CEL has only ever come on at startup, never while driving. Even then, I'm still not going into limp mode.

We'll see if TPS solves it. If not, what's the next solution? Replacing throttle body?

Also, I have a used APPS laying around if anybody wants a spare. Left the new one installed even though the old one isn't the culprit.

I'd be interested in your APPS if you still have it?

 

[Cowboy59]

trudd,
did you ever replace the TPS?

 

[trudd]

trudd,
did you ever replace the TPS?

Yep. Took care of the issues

 

[trudd]

Update: one year later and I'm getting the P1126 code again. Absolutely no change in performance, just CEL, VSC Trac, VSC Off staring at me. I'll clear the code and it'll pop back on after 4-5 startups.

I cleaned up the MAF, throttle body, took off the existing TPS and blew it out (seemed dusty) on Saturday. Put it all back together, good for two days. Then CEL on Monday morning.

I just ordered another Denso TPS - luckily they're about half the price they were last year.

 

[trudd]

Replaced the TPS with another new one. I'll admit, I'm not good with a multimeter so after some failed attempts at closing the circuit, I just eyeballed it again. I got 1 or 2 startups before the code came on again. No limp mode, truck drives fine.

I'll be doing a 2,000+ road trip in a few weeks. What else should I be looking at? I'd like to avoid a new throttle body. Is there a "calibrate the TPS for dummies" guide? I'm not worried about Limp mode, I just don't like a CEL staring back at me (and need to pass inspection in about 9 months)

 

[tacoduck]

battery. low voltage causes the christmas tree lights on many vehicles. 100 dollar fix.

 

[trudd]

I thought about that. Multimeter reads 12.8 at the terminals when the car is off. 13.5 when car is on. battery is little over 2 years old.

Spoke to a mechanic who just replaced the throttle body on a similarly aged Tacoma. Similar issue - this guy would intermittently get errors relating to the throttle body, they'd tinker on a sensor and it would disappear. Eventually things got worse over time and they all pointed to the magnetic clutch...

maybe i'm also trying to justify having just pulled the trigger on a used TB assembly.

Edit: I'll run get it load tested today. Just weird that this issue was solved a year ago (on the same battery) and now is throwing the same code. I would assume low voltage would throw multiple codes, or at least something less obscure than magnetic clutch.

 

[tacoduck]

I would buy a new battery at walmart, and if it doesn't fix it, then return it. Walmart has a good return policy. Maybe the alternator is going out...

 

[Chaser717]

Bump

 

[trudd]

Bump

Why the bump? Guess I’ll update...

well the code came back with some regularity since the last post. I Eventually developed a dead spot on the NEW APPS sensor where I lost power at 75mph and would have to ease off the gas. Learned this 1,000 miles from home while on vacation in NM. Fully loaded with camping provisions and my family of 4. The one time I tried to power through (and not let up gas) the truck choked and I had to pull over on I-40. Yay. Luckily I had the old APPS in the glovebox so I replaced it at our campsite. Drove another 1,200 miles into CO and back to TX with no issues.

Eventually replaced the entire throttle body with a used pull-off from EBay which included the TPS and APPS sensors. Should’ve done that the first time around.

 

[Chaser717]

Thanks for the update. 2000LC, 240k miles. I’m throwing the P1126 code and instead of figuring it out part by part I think I’ll just get a new TB. I see them from Toyota dealerships online for around $430. Seems less expensive then I thought from all that I’ve read but worth it to just totally resolve it. I hope.
sorry for the bump.

 

[trudd]

Thanks for the update. 2000LC, 240k miles. I’m throwing the P1126 code and instead of figuring it out part by part I think I’ll just get a new TB. I see them from Toyota dealerships online for around $430. Seems less expensive then I thought from all that I’ve read but worth it to just totally resolve it. I hope.
sorry for the bump.

You’re good! Yeah, that’s a solid move. I definitely paid to fix it twice by the time I finally solved it.

 

[aljordan]

I just logged a P1126. Nothing else. It seems the fix is a fresh throttle body. The TB is $450 with all new sensors.. The magnetic clutch motor thing is low $200s at best and mid $300s at worst. No fiddling with the TPS and other sensors to properly set them up. Just bolt on and go with the TB assembly.