Before I go under the car: The engine light came on on my way home, because of P1131. Here is some data, the live data is the last chunk the scanner collected, I’ll attach all of the data:
Your scan tool readings show the oxygen sensor on bank 1, before the catalytic converter, is sending NO signal to the pcm. This could be from a broken wire, a bad connection, or unconnected wire. The gray/red wire carries 5 volts dc (engine ON(?), or RUNNING, for sure). You can backprobe the gray/red wire, for voltage, without disconnecting anything. You could, also, backprobe the gray/light blue wire, near the O2 sensor; and, then, at the pcm 60 (multimeter set at 5 volts, then 1 volt.
Look at the wiring diagram. If there isn’t voltage at either point, you’ll have to follow the wire, with the multimeter, toward its voltage source.
I’ll post more tomorrow, but here is all I was able to discover:
PCM 91 to disconnected O2 plug: 0.3-0.4 ohms
PCM 93 to disconnected O2 plug: 0.6 ohms
PCM 71 to disconnected O2 plug: 0.5 ohms
B1S1
(PCM wire to O2 sensor wire)
white/black to white
red to white
red/green to black
grey/red to grey
B2S1
white/red to black
(the rest were too damn hard to see and were dirty to boot…)
Note: O2 sensor #11, which the error code P1131 refers to, is actually B2S1, which confuses me because I would expect it to be B1S1, since as you point out hellokit, that sensor is reading 0.000 (and has been reading that since the start of this). I figured out that it is B2S1 based on the PCM wiring diagram and checking the wire colors in the car itself.
Instead of checking resistance readings I suggest you leave things connected up and use the voltmeter to check with. Check the sensor voltage of the bad sensor B1S1 at the connections going to the PCM and see if you have a reading there. If not then check at the sensor connections to the vehicle wiring. The problem could be with the input to the PCM. You could also swap the front sensors to see if that changes things. The sensor may be bad.
Instead of checking resistance readings I suggest you leave things connected up and use the voltmeter to check with. Check the sensor voltage of the bad sensor B1S1 at the connections going to the PCM and see if you have a reading there. If not then check at the sensor connections to the vehicle wiring. The problem could be with the input to the PCM. You could also swap the front sensors to see if that changes things. The sensor may be bad.
I won’t have time to do anything to the car tonight… In regards to the B2S1 sensor, it is really difficult to get to its’ plug where it connects to the PCM wiring, it’s against the firewall, behind the engine, let alone get to the O2 sensor itself. I have yet to see the B2S1 sensor, I haven’t the foggiest idea how a mechanic is able to reach it (I know where it should be, I just haven’t see in from above or below)…
Codes were cleared last night, obviously, and after my drive to work I hooked up the scanner (the engine light never came on). No stored codes and two pending codes. HOWEVER, this time the pending codes are P0155 and P1132 (as apposed to the usual P1131) “Lack of HO2S11 Switch - Sens Indicates RICH”.
Someone has (had?) their banks confused. It’s possible that some one swapped both front O2 sensors’ wiring. Let’s be sure before “fixin” the wrong one, (again?). The reference position is from the driver’s position (when all engines pointed toward the front of the car).
FORD numbers all their engines the same way. The right hand side of the engine (from the driver’s (yesteryear) perspective) is ODD numbered cylinders. BANK 1 has all ODD numbered cylinders. Looking from the BUTT end of the engine (the end opposite the belts), the right hand side is ODD.
To find Bank 1, follow the spark plug wire, from the six-tower ignition coil, to #1 cylinder. Bank 1, sensor 1, will be on that side (before the catalytic converter). The wire numbers are stamped on top of the ignition coil: http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c1528003a8cb
The wiring diagram has the wire colors as: red/white (not, W/R); red/lightgreen (not, R/G). Let’s not confuse me, ok? Do you have your enlarged paper wiring diagram and color pencils? It’s not required, but, helpful.
The pending code for the B2S1 sensor should go away after time. I wouldn’t be too concerned about that one. The B1S1 sensor is the one that needs to be checked since the PCM isn’t seeing any signal from it. Since there isn’t a code being set for that sensor I think the most likely problem with the sensor is either it is defective or the input to the PCM for that sensor is bad. You could try swapping the two front sensors and see if that changes things. If it doesn’t, then the PCM input may be bad.
Is alldata’s data the same as FORDs? If it is, and FORD’s data is wrong; then, alldata’s data will be wrong. I don’t know; but, I do know that there are references which confuse me (I know. I know…not hard to do.).
The wiring diagram, and PCM pin chart, call PCM pin 91 “SIGNAL RETURN”. Fine; but, pin 91 OUTPUTS 5 volts dc for ALL the sensors, doesn’t it? So, how can it be a signal return path? This is important to know, for a number of reasons: The same chart calls PCM pin 60, for O2 sensor 11 (Bank 1, pre-cat.) “SENSOR 11 INPUT [to the PCM]”.
Will the real signal return path please step forward!
A more immediate problem is wiring a replacement Bosch Universal Oxygen Sensor into the car’s wiring. The Bosch reference is on page 29, step 7, of this: http://www.bosch.com.au/content/language1/downloads/Section_A.pdf
The grey wire, from the Bosch O2 sensor, goes to “Sensor signal ground”, which is? PCM 91, or PCM 60 (for the B1S1 sensor)?
It could be possible to have the AC signal ground tied to the DC bias lead Hellokit. It would be handy to have the diagram for the PCM to see if that is so. When I had a chance to look at the drawing for the system a couple of days ago I noticed that one of the sensors (B2S1?) was wired slightly different than the rest. I am not sure why the circuit is designed like that.
If I understand you correctly you state that pin 60 is the input to the PCM for the sensor so that is high side of the sensor circuit and pin 91 would be the low side or return side of the circuit for that signal.
Thanks for responding, Cougar.
Pin 60 is labeled: “Heated Oxygen Sensor #11 (HO2S)Input”. Pin 91 is labeled: “Signal Return”. Pin 91 serves 10 sensors. How can it give individual attention to 10 sensors’s output signals, AND supply those 10 sensors with 5 volts dc?
I understand about multiplexing, and circuits carrying both ac and dc components; but, the technology on this era of FORD is 14 plus years old…not, today’s stuff.
Put another way, which wire (60 or 91) does one connect (for B1S1) the Bosch Universal Sensor’s “O2 sensor output black wire” to? Which wire (60 or 91) does one connect the grey wire “O2 sensor signal ground” to?
Fig. 5 is the applicable wiring diagram: http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c1528003ad27
Surely, someone knows this stuff as old hat?! Surely.
Hellokit.
You guys are the best, really, I can’t thank you enough for taking all the time you have on this.
I haven’t been able to do anything since I last posted, except that the codes were cleared the last time I worked on the car and since then I’ve run the scanner again and the results are below. I’ve also attached the really nice PCM pinout chart from Chilton for you all. Tomorrow I will spend the day under the car trying to do everything you all have recently suggested.
Now there are two stored codes: PO155 & P1131 and no pending codes
You can add the 5 volt supply to the signal return lead of the sensor simply by using a coupling capacitor to isolate the two. The cap will block the DC component but will allow the signal to pass through. This isn’t anything new and has been used for many years in circuit design.
The return side of a circuit is usually a common ground point for devices to tie to. It may not necessarily be tied to chassis ground (and in this case it isn’t). That can be different and you can tie as many points to that as you need to, depending on the circuit design.
Looking at your pin connections, the Bosch sensor output (blk) would tie to pin 60 and the gray wire would tie to pin 91, the AC signal return lead or “ground for the sensor”.
Your picture is unreadable, even when downloaded. Did you set your cell phone camera, your pc (download and send) on their highest resolutions?
Forget about testing for crossed wires or swapped sensors. The PCM does self-tests for those situations. Then, it sets DTC (Diagnostic Trouble Codes) if it finds any. None are set.
The DTCs which are set are: P0155 for bank 2 front sensor heater circuit problem; and P1131 for no switching (from rich-to-lean, lean-to-rich) action signal in the bank 1 front O2 sensor. It stays at LEAN (low output voltage).
Now, do Pinpoint Test (DTC P1131) H24 for the signal circuit on Bank 1 front sensor: 1. Disconnect B1S1’s electrical connector. 2. Put a jumper wire into the gray/light blue wire terminal (going to PCM 60), and the other end into the red wire terminal (going to PCM 71). 3. Connect scan tool to car. 4.Turn the ignition key ON, leave the engine OFF. 5.With the scanner, read the B1S1 voltage. 6. Turn the ignition key OFF. Results: If the voltage was more than 1 1/2 volts, the wiring is ok (down to the connector). If the voltage is less than 1 1/2 volts, go to Pinpoint Test H25.
Pinpoint test H25: 1.Key OFF. 2. Disconnect PCM []and[/b] B1S1 electrical connectors. 3. Check ohms from PCM 60 to O2 (grey/light blue) plug; PCM 91 to O2 (grey/red) plug; PCM 93 to O2 (red/white) plug; and PCM 71 to O2 (red) plug. If this wiring checks ok, then, the problem is inside the O2 sensor. Replacement of the O2 is the only option.
For P0155 the heater circuit of the Bank 2 front O2 sensor, with the O2 connected, do resistance (ohms) test of PCM 94 (white/black wire) to PCM 71 (red wire). If it checks bad, disconnect B2 front O2 sensor, and check ohms on each wire (PCM 94, and PCM 71 to B2S1 plug. Then, ohms check the O2 sensor, red and white/black.
Sorry hellokit, I think that you are viewing the image file at something other than 100%. The attached PDF is the original version, it should be easier to read at any magnification.
Gasp!! Do you mean someone told you that they changed a part; but, DIDN’T?! I’m shocked and dismayed. Can such a thing happen?! ( A little sarcasm).
It’s hard to see from here; but, is that the bank two front O2 sensor? And, no, it doesn’t have any new shiny aspects. I think someone was…er…er… “mistaken” as to what they done.
Do you want to swap it with another O2 sensor to see if the DTC swaps?
On second thought, call the law and file a COMPLAINT. I think you were crooked! Seriously.
Well, I think it’s B2S1. I attached that diagram to confirm because I don’t know what is considered the front and what is the back. So here, is this correct?
Did you see the damaged wire in the photo? It’s just the insulation, I pulled it back and the wire is fine.
I have two brand new sensors that I haven’t used yet. They’re Bosch 1311 and 13117. For some stupid reason they do not say which is upstream (upstream means front?) and which is downstream… So I’m looking into that. This old one CANNOT be good, so I’m going to go ahead and change it out.