P1515 and P1221

cxkali

Original poster
Member
Jan 20, 2012
125
I was on my way home and stopped at a red light to get on the interstate today, while i was sitting there my ses and reduced engine power light came on so i check the codes and got a P1515 and a P1221 got my code reader cleared the codes and started it back up and the lights came back on tired again to clear the codes and came back on again. i cleaned the throttle body last month i double checked it today and it still looks clean was wondering if anyone could point me in the right direction as to why it would do this and what parts i should change to eliminate the problem
 

AtlWrk

Member
Dec 6, 2011
674
cxkali said:
I was on my way home and stopped at a red light to get on the interstate today, while i was sitting there my ses and reduced engine power light came on so i check the codes and got a P1516 and a P1221 got my code reader cleared the codes and started it back up and the lights came back on tired again to clear the codes and came back on again. i cleaned the throttle body last month i double checked it today and it still looks clean was wondering if anyone could point me in the right direction as to why it would do this and what parts i should change to eliminate the problem

Those DTCs occur when the PCM doesn't receive the feedback from the the throttle body it's expecting, either because the throttle has genuinely malfunctioned or there is a connection issue.

Since you've had your throttle body off recently I would start by inspecting the electrical connector on the thottle body closely. Remove it and inspect for damaged/loose wires or connectors or corrosion. Make sure the connector is fully seated in the throttle body.

It's a bit less likely but check all of the fuses very closely, particularly 23 (ETC) and any containing "PCM" or "IGN"
 

cxkali

Original poster
Member
Jan 20, 2012
125
ok ill check that out and take it for another drive and report back asap.
 

cxkali

Original poster
Member
Jan 20, 2012
125
took a look at the wires everything looks good from what i can see but still showing codes P1221 only and comes back when i reset the codes,could my throttle body have taking a dip?
 

MAY03LT

Member
Nov 18, 2011
3,422
Delmarva
cxkali said:
correction on title codes are p1515 and p1221

A short in the 5v reference wire, that the fan clutch shares with the TPS and APP sensors, can cause these codes.
Since the codes come back immediately, and you have the ability to clear codes, there is something that you can try before you throw any parts at it. Unplug the fan clutch connector, clear codes, and start the engine. It might set a p0495 (IIRC) with the clutch unplugged but you'd be looking for the P1515 and P1221 to come back.
 

cxkali

Original poster
Member
Jan 20, 2012
125
just went downstairs and unhooked the fan clutch cleared codes and started and this is what came up



P1221
P1515
P1481
P1221
P1515
P1481


total of six codes
 

AtlWrk

Member
Dec 6, 2011
674
How handy are you with a voltmeter?

With the ignition ON and the engine OFF check the following on the TB connector:
1
Meter black lead to the black/white-stripe wire
Meter red lead to the Light-blue/black stripe wire
You should see +5V
2
Meter black lead to the black wire
Meter red lead to the grey wire
You should see +5V

While I'm still leaning towards an electrical issue you can easily check for a physical problem with the throttle body with the ignition OFF:

Take off the intake so you can see the throttle plate. It should be about 20% open. Carefully move it fully closed and fully open.
You should feel spring pressure for the entire movement in both directions and it should always return to its original position. There should be no binding or sticking.
 

AtlWrk

Member
Dec 6, 2011
674
For the sake of completeness since you're going to be in there anyway:

If tests 1 and 2 come back with +5V check 3 and 4 below. These have to be done with the throttlebody connected, ignition ON, engine on or off. If you cant get the meter probe into the back of the connector you can poke a pushpin through the insulation.

3
Meter black lead to the black/white-stripe wire
Meter red lead to the purple wire
You should see a reading greater than 0V and less than 5V
4
Meter black lead to the black wire
Meter red lead to the dark green wire
You should see a reading greater than 0V and less than 5V

If you have a helping hand have them press the gas pedal up and down while you have the meter connected, the readings should change.
 

cxkali

Original poster
Member
Jan 20, 2012
125
sorry it took me so long to get back to this reply i recleaned the throttle body and hooked everything back up and it drove good for a couple of days and now im getting the same codes p1515 p1221 + a p1516
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Did you do the experiments in posts #8 and 9?
 

cxkali

Original poster
Member
Jan 20, 2012
125
no i did not but i can tomorrow since i dont have a meter but can buy one for sure.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
You might be the first person I've heard of who owned a code reader :thumbsup: before a meter. Meters are critically useful - you'll enjoy owning one. And loaning it out when your friends hear you have one. :biggrin:

But if it's not the fan clutch interacting with the circuit, you have either messed up wiring in the harness, or a bad throttle body assembly. Prepare to spend a couple of $$.
 

cxkali

Original poster
Member
Jan 20, 2012
125
yea its starting to suck that all the nightmares that come with the reduced engine power light are coming true for me i was just looking to trade the envoy.... i think its wanting to stay
 

cxkali

Original poster
Member
Jan 20, 2012
125
how would i know for sure if its the clutch fan causing the issue or maybe even the pedal assy or the throttle body what can i do to start eliminating these issues just so everyone knows it has 135k and i've never changed any parts except for the t-stat
 

cxkali

Original poster
Member
Jan 20, 2012
125
did the test in post eight and its was right at 5.02 on the meter
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
You tried it with the fan clutch unplugged, right? And the codes came right back. So it's not the fan clutch. Probably the throttle body hardware, but unless you have a buddy to swap with, you'll be shotgunning it. Inspect the throttle body wiring harness as best you can.
 

cxkali

Original poster
Member
Jan 20, 2012
125
that was with the fan clutch connected also have a new code that came up a p1120 and p1220 the lights are not coming on as soon as i turn the key on now just to clarify it took some time for this one to turn the ses and reduced engine power light on
 

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