Check Engine Light - 25, 26, 51 (1 Viewer)

Joined
Dec 22, 2015
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147
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San Francisco
I feel like I'm taking crazy pills.

First off, I want to apologize to all the Mudders for harping on this issue. Secondly, I want to thank everyone in advance for reading.

Since I've owned this truck, I get these three codes. Not all the time. And oddly enough, after I've done work, they seem to stay away, until they don't.

What have I done:
- replaced MAF sensor
- replaced O2 sensors
- replaced TPS
- replaced fuel pulsation damper

After each repair, the lights seemingly stay away for a few months. I drove 1,800 miles in December, after the new O2 sensors, no lights.

Now they're back. And even after pulling the EFI circuit, they come back on much faster, like next trip.

What else could this possibly be? The truck doesn't seem to be driving any differently too. Ahhhhhh!!!

Again, thank you so much for helping!
 

FJ Silver

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Jul 8, 2012
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New Harmony, Utah
Hey man,
I Can't really deduce from your post if you know what the codes are?
Have they come back yet?

In case you don't :

Screenshot 2018-07-31 21.52.39.png
Screenshot 2018-07-31 21.52.28.png


I noticed when I was having pressure issues in my 38gal gas tank, it would sometimes throw those run lean/rich codes.
But you've thrown a lot of parts at it already. What's your mileage like? Could have the injectors checked out.

51 is interesting, I'd read that as some electrical issue, perhaps grounding. Have you found any posts here on that #?
Does it ever have a hard time starting?
 
Joined
Dec 22, 2015
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San Francisco
@FJ Silver thanks for the reply and the kind words! I do have the 38g tank as well and it is usually pretty pressurized when I remove the cap. I'll look into that. Out of curiosity, how did you solve for that?

I think 51 has something to do with my AC. I recently had it repaired and when it's on, it makes a clicking sound like something is shorting out. Not sure where to look to being diagnosing that though.

Thanks!
 

red66toy

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Seattle, WA
@FJ Silver thanks for the reply and the kind words! I do have the 38g tank as well and it is usually pretty pressurized when I remove the cap. I'll look into that. Out of curiosity, how did you solve for that?

I think 51 has something to do with my AC. I recently had it repaired and when it's on, it makes a clicking sound like something is shorting out. Not sure where to look to being diagnosing that though.

Thanks!
The AC amplifier has a little relay on the circuit board that has to do with the compressor cycling on and off. That is the only thing I have ever heard click while my AC was running. Shouldn't be clicking fast unless your compressor is cycling on and off fast, which it shouldn't be.

Have you replaced your charcoal canister? When that gets plugged it causes the classic tank pressure issues.
 

tstockto

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Nov 1, 2017
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Somewhere between Bee Cave & Dripping Springs, TX
i was getting those same codes 25,26,51 (plus some others - 41,71). just took it to yotamasters because i was frustrated i couldn't fix it, wasn't having luck testing all the pieces, and tired of throwing parts at it. the 25,26 was a result of failed AIR system VSVs. my TPS was also bad. From the notes they gave me it made it sound like 41 and 51 were related and based on @FJ Silver 's image, that could be true. or 51 could be a few other things. The 25,26 was explained to me as air fuel ratio going too lean, computer trying to account for that, making it go too far rich, repeat cycle... the fact the computer couldn't get control of things was due to the failed VSVs. but if you look at this diagram, any one of those components there could probably account for 25,26.
Toyota_Landcruiser_FJ62_pdf__page_112_of_380_.png
 
Joined
Dec 22, 2015
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San Francisco
@tstockto thanks for sharing that! It feels exactly like what I'm suffering from. I'm not that technical, could you elaborate on where that AIR VSV is located? Thanks!
 

red66toy

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@tstockto thanks for sharing that! It feels exactly like what I'm suffering from. I'm not that technical, could you elaborate on where that AIR VSV is located? Thanks!
Should be located on the driver's side fender on the bank of three vsv's just behing the ASV valve. Not sure which one of the three. Trace the vacuum like from the ASV to the correct VSV.
 
Joined
Dec 16, 2006
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Atlanta
I get 25 and 26. I also have the 38-gallon tank. Mine runs great, but gets about 10.5 mpg no matter what I do.

1990 FJ62, no lift, H55, 33x10.50, bumpers.
 
Joined
Dec 22, 2015
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@Crewzen @Code Red not really... I found a bit of a leak in the vacuum and fixed it but the light still comes on, sporadically. I drove 800 miles to Nevada, no light. I drove 10 miles around town, light comes on. It doesn't make any sense!

I also have the 38g tank. Seems to run fine and I too get around 10.5 mpg sometimes closer to 13 on the highway.
 

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