QuestionQUESTION: Check-engine light. Sometimes dies when idle, hot or cold, 1 minute after start or 10 hours running well then dies suddenly.
Key-dance shown codes 12,23,33,71.. Disconnected one by one all 4 sensors (TPS,MAP, Intake manifold temperature, A\C - 5v supply is +5V everywhere. Checked Intake temperature sensor resistance under different temperatures - it seems to be fine. Checked EGR solenoid connector - no 5v.. It should be there? (i doubt). Where else to check?..
ANSWER: Hi Vlad,
All the codes relate to devices needing the 5v supply to work properly so I would look for one of the sensors or its 5v supply wire to be shorted to ground. The 5 volt output is from pin 61 at the pcm so you could look at the load on that wire and see how it changes as you remove various of the items (MAP, TPS, AC pressure sensor, intake air for 2.0/2,4L only). The egr solenoid should show 12v on the dark blue/orange when the engine is running, and the gray/yellow would be switching from 12v to 0 as you oscillate the thottle (under pcm direction at pin 40, no 5v used with the egr). So check for the possibility of a burned through/shorted 5v wire (violet/white).
Roland
---------- FOLLOW-UP ----------
QUESTION: Hi Roland, thank you for attention to my problem.
- i checked voltage on PCM at pin-61, 5v with all and without all these sensors, no changes as i pull connectors out.
- checked resistance between pin-61 and ground (at battery connector), found abnormal difference as i touched AC pressure sensor. Checked wire harness at connector, nothing burned/cut. It appears to me that problem is IN sensor. Then.. Why i still see same codes (12,71,33,23) even if i disconnect AC sensor completely?.. Problem is elsewhere else?
I'm stuck again. As i guess, there is no way i can easy check that sensor (its under pressure?). Please give me a hint where else to check.
P.S. I also have ABS light.. but i assume its a different module and plan to take care of it AFTER that ugly 71-33-23 problem. Cant it somehow cause one another?
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Hi Vlad,
Did you solve that intermittent problem? If you would like to tell me there is a "Thank/rate the expert" button below which if you click will take you to page where you can "comment".
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Roland
Hi Vlad,
The codes will stay in the memory unless you disconnect the battery for a few minutes, which will erase all the codes except 12. Then drive it and see what codes return.
The AC pressure sensor can be changed without removing the refrigerant, just use a 3/4" open end wrench. You will need a new o-ring when installing it. There may be a small amount of pressure released upon removal.
I don't understand what you mean by 'abnormal difference as i touched AC pressure sensor', what do you mean by 'touched', did you disconnect the electrical plug, or what?
In any case, erase the codes and see if 71 comes back or not.
On the 23 code, is the resistance of the sensor as measured across the terminals about 10-14K ohms when cold, and does it drop to 700-1000 ohms when warmed to about 200F? If not, then that sensor is probably bad.
The only items drawing on pin 61 are the TPS, a/c sensor, intake air (or combined intake air/map if the engine is a 2.0/2.4L). So if you don't find any issues with the sensors or their wirings, and the voltage is far below 5V then the pcm is bad; otherwise if at 5V then I don't see why you would have a 71 code.
Roland
