$25 challenge

[Crossthreader]

Here's a bit of theory on O2 sensors that may help you get going in the right direction. The sensor does not use a reference voltage from the PCM. It does generate an output voltage when it at 600F or hotter. The heater is there to get it up to temp faster and allow better emission control during warm up. The output voltage is between 0 and 1 volt, with 0.4 volt being the threshold of rich or lean. In normal operation, the sensor 1 and 2 voltages go above and below 0.4 v as the pcm adjusts fueling. Sensor 3 is after the cat, and doesn't change much if the cat is working.

I know it is not good practice to apply information from a different M.Y. but my 99 manual shows PCM Pin 90-Brown/White as reference voltage out and Pin 91-Gray/Red as sensor ground. It might be worth your time to check if this is the same on yours.

Paul

 

[Crossthreader]

That's what happens when I take too long to compose a reply. Oh well, it was a good effort. As far as PATS goes, there is no easy way around it.

I may not get time to try tomorrow, but as soon as I get a break, I can check my 99 4.0. Are you looking for live data from the O2 sensors and fuel trim, or is there something else I should check for?

Paul

 

[adsm08]

I've been following this and pondering. I still haven't seen you post anything about the actual function of the VSS, as tested at the VSS.

Next, yes the O2 sensor creates it's own voltage. You say you have seen this voltage with a meter? This information is reported back to the datalink when requested by a scanner, if the computer sees the information coming in.

The next thing I want you to do is this: Unplug an O2 sensor. Using a fused wire jump a heater power line to the signal line. When you do this the PID for the chosen sensor should go to 1.3V and hold there.

 

[bort]

Sorry about not getting back to you about the vss, I'm doing this without help and I've been leary about putting it on stands and getting under there with it in gear on my dirt driveway. Could I chuck it in the drill press and check the ac voltage that way? Or does it need that trigger you were speaking of?

As far as the O2s they are making voltage (glad I've got a better grasp in that now) and that voltage is getting up to the computer. At least to the 104 pin connector. I think the computer is using the input because it responds to me disconnecting and reconnecting the sensors (bank 2 is the easiest to mess with). I will definitely give the jumper wire a shot. In the next day or two.

I know it is not good practice to apply information from a different M.Y. but my 99 manual shows PCM Pin 90-Brown/White as reference voltage out and Pin 91-Gray/Red as sensor ground

I dont see it as bad practice in this case. The wiring is supposed to be the same 96-99. Pin 90 is definitely VREF out but it does not go to the O2s it's for the TPS and DPFE. That falls on my misinterpretation of how the O2s work. And pin91 is the sensor ground, as well as for everything else. All good there.

Are you looking for live data from the O2 sensors and fuel trim, or is there something else I should check for?

As far as somebody checking I was wondering if maybe the 97s didn't actually provide the O2 and fuel trim data to the DLC. Or if I have a bad connection from computer to DLC so my PIDs are false? Would I still have the other data then?

Off topic:

Looking for 95-98 manual trans pedal bracket. Conducting an experiment for the betterment of all Ranger-kind

.

Please tell me that's about the elimination of the frequently failing slave/bearing combination!?

 

[bort]

Sorry I've been missing and haven't reported back. Finals week this week, my last semester ever so I don't want to screw it up.

Update, to adsm 08, I tried the fusible link on the O2 sensors, used the plug off of an old sensor and put terminal connectors on the end. When I plugged it in with hot heater feed to sensor out it instantly made the truck run like crap, but I still had 0.000 on the pids.

Checked the continuity from beginning to end of all the connections at the OBD2 port. All was correct. I did however notice the TPS was reading 18.8% at closed throttle, and would go 100% at about 3/4 pedal. I adjusted that then ran out of gas so I dont know the end result. I'm hesitant to put gas in since I plan to pull the bed and replace the pump when I do the leaf swap. So that result may have to wait.

As far as the vss, I was still wondering if it had to be checked in the truck or if I can check it out somehow? Beyond my knowledge. I might try to get to that tonight.

Frankly I'm about to give up on the pids and just tackle the rear suspension work. Im thinking that if I can get it on the road, I can flog it, make it throw codes and have some sort of jumping off point.

Thanks to all again for your replies and advice, I hope that somewhere down the line I will have the chance to pass it back or help somehow. If anybody has some Cummins 6bt problems I might be of some help, thats all the company trucks I work on. That and I fabbed upper control arms for my 01 ranger edge, I was able to cycle 9.5" on factory lowers, 33x12.50s, and #1 bars from a sport track. Also did the 31 spline disc explorer limited swap on it. Gonna do it again. So ask away.

thanks again, kirk

 

[Snoranger]

Why dont you take the $25 dollars and put it to good use and support the forum... become a premium member.

 

[PlumCrazy]

I had a similar problem back in the day. Turns out the harness going to the O2s, VSS, and reverse switch was pinched between the transmission and engine cutting all the wires. Turns out the PO didn't notice the 1/8" gap between the trans and engine.

-PlumCrazy

 

[KDXRider]

If you still have not found the problem

Unplug all the sensors affected
study your wiring diagrams and have them handy
get two long jumper wires to connect to your meter leads
Unplug your pcm and check for continuity from the sensor plug back to the corresponding pin on the pcm harness
you should back prope the pcm harness but i would carefully use the other lead to probe the inside of the plug on the sensor end as a lot of times the issue is right there at the plug and ford offers nice replacement pigtails for every plug problem i've ever had.

Let me know what you find