Check engine codes 12 and 71

[Griswald]

Going to start a fresh thread here now that I've pulled the codes:

1989 Runner, 22 RE.
anyone have any luck finding the culprit of these?

Code 12 - Engine speed (RPM) sensor -circuit
Probable cause - Wiring, RPM sensor, ignition module, ECM

Code 71 - Exhaust gas recirculation (EGR) system malfunction
Probable cause - Hose leak/blockage, wiring, EGRT sensor, EGR solenoid, ECM

any advice is greatly appreciated! thanks!

 

[Ahlem]

There's a youtube video of someone diagnosing the EGR code on a 3.0 that's pretty handy.
He took off the vacuum line to the egr valve and applied vacuum at idle and his motor stumbled and stalled out, indicating the EGR valve worked. He then checked the vacuum lines and found no vacuum on one of them that had a hole in it. He got off easy. I am going to unplug both ends of the vacuum lines that go to the part just upstream from the egr valve and apply compressed air to see if there is blockage. Others have wired in a resistor somewhere baling wire style and solved their problem but I'm not ready to go there.
We don't have to have vehicles tested in Michigan so this is more of a nuisance.

 

[typayton27]

There's a youtube video of someone diagnosing the EGR code on a 3.0 that's pretty handy.
He took off the vacuum line to the egr valve and applied vacuum at idle and his motor stumbled and stalled out, indicating the EGR valve worked. He then checked the vacuum lines and found no vacuum on one of them that had a hole in it. He got off easy. I am going to unplug both ends of the vacuum lines that go to the part just upstream from the egr valve and apply compressed air to see if there is blockage. Others have wired in a resistor somewhere baling wire style and solved their problem but I'm not ready to go there.
We don't have to have vehicles tested in Michigan so this is more of a nuisance.

I'll have to check out this video. Do you have a link to it you can provide by chance? New owner of a '92 3.0 4x4 Manual and have just pulled the codes... 12, 14, 41, and 71. Engine turns, seems to runs fine with no alarming noises or performance issues. Throttle feels fine and transmission feels smooth. Car has idled for 15+ minutes under my watch and I've noticed the idle fluctuates at around 700-1200 rpms. Trying to figure out why these codes may be displaying, maybe they're all connected to a similar issue, any insight would be helpful. I'm not the most knowledgeable on these cars at all, so anybody who has prior dealt with these codes that found solutions please feel free to share what you've found. *Also if it matters in context of code 71, I purchased the vehicle without a catalytic converter, recently installed a new cat about 5 days ago.