I was poking around under the dash fixing the PO's terrible stereo wiring job when I noticed the IGN 7.5A fuse was popped. The truck was running fine, maybe hesitating a small amount, but was getting terrible economy (like 350-400km on the highway to a tank of gas). I replaced the fuse and the truck feels like it's running a bit smoother but it's too early to tell if it affects the economy. From what I can gather in the wiring diagram the IGN fuse controls the charge light and the emissions computer and related things (like fuel cutoff, VSV, and so charcoal canister and everything). Presumably that was the problem with my crappy mileage, am I right?

So while I was working I pulled the codes and got a 14, 41, and 51. I then pulled the EFI fuse for a minute and the 14 and 41 went away (presumably due to the new IGN fuse). The 51 remained, but I can't find it listed in my Haynes manual. What's a code 51?

This is on my 89 4Runner.

 

According to my list they are as follows

System Affected Probale Cause

14 Ignition Signal Ignition Coil , Ignitor Or Circut ,ECU

41 TPS Signal TPS Or Circut , ECU

51 Switch Signal Accelerator Pedal Or cable A/C Switch Circut , A/C Amplifier ,ECU , Neutral/ Start Switch or Circut TPS Sensor Or Circut

Hope this helps As for what to do I would start by pulling the pos battery cable and leave it off for about 1 min then replace it and run the truck and see if you get the code/s again and then start narrowing it down from the list as shown.

 

As I said, I reset the ECU and the only code left is 51. In the FSM it seems like it's a code thrown if you're not in Neutral or the like when you jump the diag terminals. Am I right?

 

51 means most likely you tps is out of adjustment

 

which it likely is. i'll pull the throttle body and clean/adjust it. thanks!