Help Diagnosing
- Thread starter bmvalentine
- Start date
Yes, a faulty new part happens and when it does, it can be a nasty curve ball.
Just confirmed, using the same troubleshooting as the video, tps is good.
Ok. Now test the map sensor.
-Key on, engine off: Backprobe pink/yellow wire. Should be 5 volts.
- Key on, engine off: Install back probe in signal wire (VIO/BRN) unplug sensor, should jump to 5 volts.
- Incandescent test light connected to battery positive, touch ground wire DK BLU/DK GRN. Test light should light.
- Plug sensor back in. Clear codes.
- Back probe the signal wire again. Start vehicle. Map sensor signal voltage should read below 2 volts at idle and above 3.5 volts with the pedal to the floor.
Edit: also, now that we’re dealing with MAP, make darn sure your throttle body is cleaned. Too many times I’ve seen where MAP related faults are because of carbon build up. Vacuum leaks are also something to keep in mind, however, the fuel trims you posted, although maybe a little high, don’t suggest a huge vacuum leak. You also don’t have lean codes, so I wouldn’t focus on that too hard right now.
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I just stick my cheap endoscope with the side camera through the oxygen sensor holes
I’ll have to test the MAP tomorrow, I just cleaned the whole throttle body very well yesterday, so should be good on that front.
Ok, got the MAP sensor tested, it tested good. My wires were different colors which threw a curveball, but pretty easy to figure out which was what with the multimeter.
Your best bet is to drive it until it sets the code, and then look at freeze frame data to see what it’s griping about. Did you clean your throttle body? A dirty throttle body can give screwy MAP readings. That’s actually in a note straight from your jeep manual regarding this DTC.
Your scan tool should have a function called freeze frame data when you click on the trouble code. It’s a picture of all of the OBD2 data as it was the moment the PCM triggered a DTC. It allows a trained eye to see why the DTC was set and can be a real aid in troubleshooting intermittent faults.
Well according to this chart you'd need to be at 15000 ft for 15.1 inHg.
https://www.sensorsone.com/altitude-pressure-units-conversion/
-Mac
https://www.sensorsone.com/altitude-pressure-units-conversion/
-Mac
Looks like there's 12 pages of data, but you only posted 2 of them.
Right, but that would only be an issue if it was reading 15.1 inHg with the key on engine off and he was at sea level. He's at 3600 RPM so the engine is creating a vacuum.
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This is the frustrating part with "troubleshooting" when you only have access to OBD2 data. OBD2 is the minimum data that was required by the government for that year of vehicle. OEM data is much more in depth. The troubleshooting charts (attached) provided by Jeep assume that you have access to OEM data via the DRBIII. Many aftermarket scan tools have access to this same data. I believe your scanner does not.
For instance, in your case Jeep's troubleshooting tree has you looking at live data of the TPS and Map voltages on the scan tool. This particular DTC is upset with the fact that TPS and MAP signal return voltages are out of range at certain throttle positions. Your OBD2 data, or at least what you posted, is giving us inHG and Load %, instead of Map voltage and TPS voltage. I'm sure some guru out there has a chart or something that would be able to convert these values to voltages, but I'm not that guru.
Long story short, this is where a quality scan tool comes into play. It's one thing to backprobe and measure voltages at sensors. Many times we can catch a sensor acting stupid with these tests. But when those methods check out just fine, it requires looking into the PCM. Unless you've verified that the PCM is receiving and translating these signals properly with the use of OEM live data, it's almost impossible to truly "troubleshoot" the issue.
Post the rest of the pages of data just in case so we can see if Map and TPS voltages are listed.
For instance, in your case Jeep's troubleshooting tree has you looking at live data of the TPS and Map voltages on the scan tool. This particular DTC is upset with the fact that TPS and MAP signal return voltages are out of range at certain throttle positions. Your OBD2 data, or at least what you posted, is giving us inHG and Load %, instead of Map voltage and TPS voltage. I'm sure some guru out there has a chart or something that would be able to convert these values to voltages, but I'm not that guru.
Long story short, this is where a quality scan tool comes into play. It's one thing to backprobe and measure voltages at sensors. Many times we can catch a sensor acting stupid with these tests. But when those methods check out just fine, it requires looking into the PCM. Unless you've verified that the PCM is receiving and translating these signals properly with the use of OEM live data, it's almost impossible to truly "troubleshoot" the issue.
Post the rest of the pages of data just in case so we can see if Map and TPS voltages are listed.
The scan tool is counting a line item not pages. So there are 12 lines of data.
The “Check Gauges” light came on with a beep today. First time that has happened…I will be going through the troubleshooting matrix probably over the weekend. How likely is a PCM or ECU failure?
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