I looked at the image, but, the resolution wasn’t good enough to tell what color the damaged wires were. So, what colors were the damaged wires? By knowing the wire colors, we can tell which circuits they are in; though, not, where in that circuit they are.
the solid red wire was the only one that needed fixin’
Drove another 15 miles today. This time after the first mile P0135 and P0155 popped up as PENDING. Which almost gave me a heart attack. They remained as Pending for the rest of the day. No CEL. However, on the scantool itself, it describes “pending” codes as codes that come up either during the current drive cycle, or the LAST drive cycle. Sooo, maybe these codes are just relics from before I fixed the car? It is very unusual for the CEL to not come on by now…
Tomorrow will be the best test, the car will be driven intermittently for 40 miles. If nothing is wrong anymore, then I would think that those pending codes will go away, and all the necessary drive cycles may complete successfully as well.
CEL came back on: P0135 and P0155
After the first mile of driving this morning the CEL came back on. Yesterday at the end of the day both O2 Sens Htr tests were displayed as Inconclusive, but this morning after the CEL came on I checked the I/M screen again and everything is listed as OK (or NA) except the EVAP System Monitor test. So, the car obviously was waiting until the O2 tests were done before setting the Pendings as Stored.
I guess the next thing is for me to run the various tests you both proposed within the last few posts to confirm or disprove that the PCM is really the culprit.
…CHECKING OXYGEN SENSOR HEATERS WITH A SCAN TOOL
The DTCs P0135 and P0155 come on showing a problem with the two front oxygen sensor heaters. We need to determine if the front oxygen sensor heaters are working. Here’s the procedure: With the oxygen sensors COLD (ignition switch not even turned to ON for, at least, 30 minuets prior to test), connect the scan tool. Turn the ignition switch to ON (leave engine off). Observe, and record an oxygen sensor with the scan tool for about 1 1/2 minuets as the oxygen sensor heaters heat the oxygen sensor sensing elements to 600F degrees, IF they are working properly.
The oxygen sensor voltage should start at 450 mv, steady dc, and gradually go down to less than 125 mv if there is NO raw fuel vapor in the exhaust in contact with the oxygen sensor sensing tip; OR, the voltage will gradually go above 650 mv steady dc, if there IS raw fuel vapor in the exhaust in contact with the oxygen sensor sensing tip.
Well, I could show you a fancy graph for the front two O2 sensors… but graphing zero isn’t very fun…
I did the test with my scan tool. I could not start the test with the ignition OFF, but I did not have a problem doing it within 1.5 min of ignition ON (engine OFF). I did the test 4 times in a row and each time the front two O2 sensors only ever read “0.000” volts.
Current scan tool data, for what it’s worth:
Stored Codes
P0135 O2 Sensor Heater Circuit Bank 1 Sensor 1
P0155 O2 Sensor Heater Circuit Bank 2 Sensor 1
View Freeze Frame
DTCFRZF P0155
FUELSYS1 CL
FUELSYS2 N/A
LOAD_PCT(%) 54.5
ETC(?C) 90
SHRTFT1(%) -2.3
LONGFT1(%) 2.3
SHRTFT2(%) -3.1
LONGFT2(%) 2.3
RPM(/min) 1776
VSS(km/h) 24
Control Module
$10 SAE J1850 PWM
Since DTCs Cleared
MIL Status ON
Misfire Monitor OK
Fuel System Mon OK
Comp. Component OK
Catalyst Mon OK
Htd Catalyst N/A
Evap System Mon INC
Sec Air System N/A
A/C Refrig Mon N/A
Oxygen Sens Mon OK
Oxygen Sens Htr OK
EGR System OK
And what of the rear oxygen sensors? How did they respond to the test? It’s imperative that the condition of cold oxygen sensors be strictly adhered to; otherwise, the test results are invalid.
For the first 30 seconds B1S2 stayed at 0.005V; B2S2 started at 0.090V and finally went up to 0.100V.
I’d have to wait for the sensors to cool down (it is about 60F outside) if you need more data than that. In fact, I’ll do it again in an hour just to be safe. And I’ll record the rears three times, which is the max, to get more data.
EDIT
I did the test again with the scan tool an hour and half later. I was able to get the scanner to start recording all 4 sensors about 15 seconds after I set the ignition to ON (engine off). I recorded data for about a minute and a half and B1S1, B1S2 and B2S1 stayed at zero. B2S2 stayed at 0.005V. It is 53 degrees F outside.
Yes, we’re having fun, now!! The weather is nice and cool, and the oxygen sensor heater will cool fairly quickly.
Very low voltage is expected from the oxygen sensor when the air in the exhaust is just air (no fuel). Let’s try it the other way…with fuel. When the oxygen sensor is heated, by its electrical element OR hot exhaust gases, it will send a higher voltage for high levels of fuel in the air in the exhaust pipe (engine running, or not).
Disable the ignition (spark) by disconnecting the control wiring to the ignition coil, or ignition module.
To get fuel into the exhaust pipe for the oxygen sensor to sense, there is a way to do that: Spray fuel into the intake. Very quickly turn the ignition key from OFF, to START for 5 seconds (crank the engine for 5 seconds), and, immediately, turn the ignition back to OFF; Connect the scan tool and record the oxygen sensors as you did before.
Oxygen sensor voltages should rise to above 600 mv as the electric element heats the oxygen sensors to their operating temperature of 600F degrees. If it doesn’t, there is a problem with the oxygen sensor circuit, the PCM, or the oxygen sensor heater. This will require further troubleshooting.
I’m sorry hellokit, but I’m afraid I need more detail when you say “Spray fuel into the intake.” I have a habit of taking people too literally sometimes, so when I type out what I think you mean, it sounds crazy (and dangerous?) when I read it back…
You handle flammable liquids all the time don’t you? How about when starting the bar-b-cue? Or, that lawn mower?
It would probably work best if you put one (1) ounce of gasoline into a spray bottle, use a straw (if you have one) and spray the gasoline into the large plastic intake tube. There’s usually a smaller rubber tube you can pull out of the larger tube, spray, and reconnect. Something stuck into the tailpipe would help to keep the gasoline vapor inside the exhaust pipe.
Do you mean one of the small tubes attached to the accordion-style air intake tube where the air filter is?
Yes, this intake tube: http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c1528003aacf
…TESTING OXYGEN SENSOR HEATERS WITH AMP METER
Use a multimeter and set it up for taking amp readings, or, use this fuse adapter amp meter: http://www.toolsource.com/fuse-buddy-tester-blade-p-98602.html On Taurus, PCM pins 93, 94, 95, and 96 are the connector pins for the 4 oxygen sensor heaters.
- Remove the 30A fuse that supplies power to the PCM Power Relay. Insert the multimeter test probes into the fuse socket, or install the fuse adapter amp meter.
- Disconnect the PCM (engine computer) electrical connector.
- Put a jumper wire into the PCM terminal (PCM 93, or 94, or 95, or 96) for a chosen oxygen sensor heater, and attach the other end of the wire to ground.
- Turn the ignition switch ON (engine off) and observe the amperage indication on the amp test gauge for 4 minuets.
- Turn the ignition switch OFF.
- Disconnect the jumper wire for the first oxygen sensor heater tested, and put the jumper wire into the PCM terminal for the next oxygen sensor heater to be tested. Attach the other end of the jumper wire to ground.
- Now, no wait is necessary because only one oxygen sensor is being heated each time. Turn ignition switch ON and repeat the check as you did the first oxygen sensor heater.
…CHECKING OXYGEN SENSOR HEATERS, AND PCM, USING A CLAMP-ON DC AMP METER:
Use a clamp-on dc amp meter (the preferred type of electrical test meter for these amperage measurements). Here is an example of a clamp-on amp meter: http://www.amazon.com/Extech-MA120-Ampere-Current-Detector/dp/B000BEZV5O/ref=sr_1_2?ie=UTF8&s=hi&qid=1224767921&sr=8-2 ],
- Clamp the amp meter probe around the selected PCM oxygen sensor heater wire (PCM 93, or 94, or 95, or 96). Select a dc amp setting of from 0.0 to 10 amps dc.
-
Ensure that the ignition switch has NOT been switched ON within the last 30 minuets. Now, turn the ignition switch to ON (engine off). Begin observing the amp test meter, and observe for two minuets.
To test more than one oxygen sensor, you must wait for 30 minuets with the ignition switch OFF; or, you could have disconnected the oxygen sensors not being tested.
Desired results: the amp meter should read between 0.4 and 3.0 amps dc for about 2 minuets; then, go to zero amps.
If the amperage isn’t correct, there is incorrect voltage, high resistance, or the PCM isn’t closing the switch to let current flow through the oxygen sensor heater.
I’m not surprised the codes for the heaters came back though I was really hoping that the wire repair was going to fix the trouble. Since past testing on the PCM indicated that it was the problem it looks to me that is really the case.
I thought of another easy test that could be done to verify current can flow through the front heaters if you want to try that Matthew. First remove the connector to the PCM. Get something like a paper clip that will fit into the pins of the PCM connector. Install it in pin 71 of the connector. Then get a test light probe and connect the clip lead to ground. Tie a test lead to the positive battery post and clip it to pin 71 and keep that connection isolated from touching anything else. Then touch the probe of the test light to pin 93 of the PCM connector. If the heater circuit is good the light will turn on and verify that the circuit is ok and will flow current through the heater. Next, move the probe connection to pin 94 and do the same thing to verify that heater cicuit. We already know that 95 and 96 are ok but if you want to test them also then go ahead. You should have a pretty bright light on each of the connections. This test will again confirm that all 4 of the heater cicuits are ok, up to the PCM at least, and you are done testing the heater circuits as far as I can see.
You may not even have to bother tieing pin 71 to power. I can’t remember for sure but if I remember correctly, power may come from another source and turning the ignition on will send power to the heaters even with the PCM connector removed. I would have to look at the drawing again to verify that.
Something as complex as PCM wiring, you need this wiring diagram: http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c1528003ad27 Click on Fig. 4, or Fig.5.
The jumpering power to PCM pin 71 isn’t necessary to get power to the oxygen sensors. Power is available to them when the ignition key is turned to ON. There IS power to the oxygen sensors if the PCM connector is disconnected.
Cougar’s method of checking the oxygen sensors brings an idea on how to check the current flow of the oxygen sensors WITHOUT cutting wires, and STILL use a multimeter to measure the current amperage. This test won’t include the PCM; BUT, if the oxygen sensor heaters work ok, and have the correct amperage, the fault will HAVE to be in the PCM.
… TESTING OXYGEN SENSOR HEATERS FOR AMPERAGE.
- The ignition key must have been OFF for 30 minuets to have cool oxygen sensor heaters to test.
- Disconnect the PCM (engine computer) connector.
- Place a fine wire (staple, needle, etc.) into PCM terminal of the oxygen sensor heater you want to test. PCM terminal 93 for bank 1, front heater; PCM 94 for bank 2, front heater; PCM 95 for bank 1, rear heater; PCM 96 for bank 2, rear heater.
- Connect the positive multimeter test probe to the chosen PCM terminal, and attach the negative probe to ground. Set multimeter to the 0.0 to 10 amp dc range.
- Turn the ignition key to ON (engine off), and observe the dc amp readings two minuets. The value should be between 0.4 to 3.0 amps dc.
You don’t have to wait until the untested oxygen sensor heaters cool because they haven’t been heated. - Turn the ignition key OFF. Make the connections for the next oxygen sensor heater. Repeat same actions as for first heater test.
- Continue tests until all oxygen sensor heaters have been tested.
RESULTS?
Thanks for verifing the point about the power source to the heaters Hellokit. I thought that was the case but I couldn’t remember for sure.
mfaeber,
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