OP
Quick advice for a French owner struggling with P0340 code
- Thread starter Maverick26_Fr
- Start date
Well it's easy to test the pinout, just unplug the sensor and see if you measure 5V (key on, engine off) against the middle pin as ground. Whichever pin has 5V on it will tell you which diagram to use.
OP
Hello
Yes thanks.
I have already made this check. Wiring is ok between pcm and sensors, and I have the 5V incoming of them.
Both have been replaced by the same 560xxx part.
Is there another components to check which should cause this issue (no ignition)?
I have checked too the Temperature sensors.. about 10kOhms. Seems ok.
Thank you for your help
I think at this point I might back probe the cam & crank sensor signal wires at the PCM. Did you already test continuity between the sensor plugs & the PCM? You can measure the signal while the jeep is running, but with a multimeter it can be hard because it's basically a 0-5v square wave, and a multimeter isn't going to show that sort of thing very easily. That's why I used that cheap oscilloscope, so I could see that waveform.
I'm also wondering if you measure the voltage on the 5V reference wire while you crank, make sure it's not dropping under load. I'm close to out of ideas.
I'm also wondering if you measure the voltage on the 5V reference wire while you crank, make sure it's not dropping under load. I'm close to out of ideas.
OP
Hello 
To update
- I have tested the continuity between sensor plugs & PCM : ok
For the moment, I haven't any oscilloscope to ensure that the square signal is incoming
Two little questions:
1. I have checked too the coil (resistance seems to be good but I will replace by security). My part has the number 56027966 and I am advised to order the following one :https://shop.asp-eberle.com/en/coil-ignition-2.5-l.-4.0-l.-id-0417.20 with number 5234610 (crown). Do you know if this should fit on my 97 TJ 4.0 ? I guess yes, but I am wondering why this is not the same number.
2. I have tested the voltage on the Crankshaft connector (with both crankshaft and camshaft sensors disconnected), when contact is ON : I can see the 5V on the pin 1
And I have too 5V on the pin 3 => I am wondering why?? It should be 0V no ? (the crankshaft sensor is disconnected when I check the voltage on the plug)
I have not the TJ97 electrical diagram (below the 2004), but I guess that it's approximately the same.
Any opinion on this please ? :s
Thank you for your help
To update
- I have tested the continuity between sensor plugs & PCM : ok
For the moment, I haven't any oscilloscope to ensure that the square signal is incoming
Two little questions:
1. I have checked too the coil (resistance seems to be good but I will replace by security). My part has the number 56027966 and I am advised to order the following one :https://shop.asp-eberle.com/en/coil-ignition-2.5-l.-4.0-l.-id-0417.20 with number 5234610 (crown). Do you know if this should fit on my 97 TJ 4.0 ? I guess yes, but I am wondering why this is not the same number.
2. I have tested the voltage on the Crankshaft connector (with both crankshaft and camshaft sensors disconnected), when contact is ON : I can see the 5V on the pin 1
And I have too 5V on the pin 3 => I am wondering why?? It should be 0V no ? (the crankshaft sensor is disconnected when I check the voltage on the plug)
I have not the TJ97 electrical diagram (below the 2004), but I guess that it's approximately the same.
Any opinion on this please ? :s
Thank you for your help
Do you know that the TJ Resources form has parts lists and factory service manuals that you can download? Check it out:
https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
From the 1997 Parts Manual:
It looks like the OEM coil is still available from Jeep, but it's very pricey. I don't know if aftermarket coils are acceptable substitutes or not, though. These days, a lot of the aftermarket stuff is junk. Hopefully someone else with a 97 TJ can add some comments to this thread.
That does appear to be the correct pinout for a 97, according to the manual in the TJ Resources section. I wouldn't expect you to see 5V on the signal with the sensor unplugged. Oddly, the P0340 code is for no camshaft sensor pulse detected, not crankshaft sensor. It seems that you have a short between the 5V sensor supply from the PCM and pin 3 somewhere in your harness, or your PCM has an internal short. With the crankshaft position sensor unplugged, do you have continuity between pins 1 and 3 on its connector? That would indicate a short somewhere...
you will see 5V on the sensor until something passes through the sensor, which then pulls the signal down to ground.
With the sensor unplugged, as he noted? He said that, with the sensor unplugged, he's seeing 5V on both the supply and signal pins on the harness connector. Unless I misread...
Did you recently replace the rotor and distributor cap? Have you checked to see if the rotor and distributor cap are in good condition? No scaling on the terminals inside the distributor cap? No hairline crack in the cap? No moisture in the cap? Do you have the correct rotor? I know at one time auto parts stores called from the wrong rotor in their look-up database for 94/95 YJs with 4.0 engines. I seem to recall early 97 TJs were built with the same rotors as 94/95 YJs until the inventory of YJ distributors was exhausted.
OP
Hello
I confirm, I don't understand why I find a 5V on PIN3 (signal).
I have made the test again a few seconds ago to confirm, with Crankshaft sensor disconnected. Here are what I can see on the connector sensor:
1. I have found 5V between ground PIN and Signal PIN
2. I have found 5V between ground PIN and Power Supply PIN
3. When the car key is removed : I can see about 1k Ohms between Supply PIN and Signal PIN (when PCM connector is plugged): Why???. If I remove the PCM connector (black one), infinite resistance.
I will be interested by the result if a TJ97 Jeeper could do the test #3 .
PCM issue ?
Thanks
OP
Hi
I have replaced the diz cap about 6 000 miles ago, some years ago. No scaling, no moisture (the jeep sleeps in a dry garage).
This problem had been recurring for several months (ignition cuts out once a week) until I had a simple oil and filter change, and since then it's been impossible to restart. Error code P0340.
OP
Thanks Sab
I have downloaded some of these manuals. I wasn't aware of this nice post.About P0340 code, I have been advised by an adaptable Jeep parts sellers to start to remplace Cranshaft Sensor.. In the manual, it is noticed too that I can be caused by his part.
I replaced the cranshaft sensor : KO
I replaced after that the camshaft position sensor : KO too
Note: There is an error in this post, please see Post #38 for the corrected version.
I don't think so. I think it's the PCM. Here's why:
#2 indicates a short between crank signal and sensor power. The last sentence in #3 that I bolded indicates that the short is in the PCM. If it was in the harness, unplugging the PCM would make no difference.
Paging @Wranglerfix - Mark, have you seen shorts between crank position sensor signal and sensor 5V power inside the early PCMs? Is that a typical issue?
I don't think so. I think it's the PCM. Here's why:
#2 indicates a short between crank signal and sensor power. The last sentence in #3 that I bolded indicates that the short is in the PCM. If it was in the harness, unplugging the PCM would make no difference.
Paging @Wranglerfix - Mark, have you seen shorts between crank position sensor signal and sensor 5V power inside the early PCMs? Is that a typical issue?
Last edited:
Did I miss something? Yes, 5V at the supply pin referenced to ground should be expected. That's not what leads me to my conclusion. He said that he has 5V on the signal, referenced to ground, with the sensor unplugged. He also has continuity between the supply 5V and the signal with the PCM plugged in, and that opens when the PCM is unplugged. That is what lead me to my conclusion - there is a short between supply 5V and crank position sensor signal inside the PCM.
Well, shoot. Now I can see the problem. I referenced the wrong point. Apologies for the confusion. Let me re-do Post 35:
I don't think so. I think it's the PCM. Here's why:
#1 indicates a short between crank signal and sensor power. The last sentence in #3 that I bolded indicates that the short is in the PCM. If it was in the harness, unplugging the PCM would make no difference.
Paging Wranglerfix - Mark, have you seen shorts between crank position sensor signal and sensor 5V power inside the early PCMs? Is that a typical issue?
I don't think so. I think it's the PCM. Here's why:
#1 indicates a short between crank signal and sensor power. The last sentence in #3 that I bolded indicates that the short is in the PCM. If it was in the harness, unplugging the PCM would make no difference.
Paging Wranglerfix - Mark, have you seen shorts between crank position sensor signal and sensor 5V power inside the early PCMs? Is that a typical issue?
Hey, Maverick26_Fr, I've learned something new in another thread that may explain the 5V on the signal you're seeing with the crank sensor unplugged. Apparently there are pull-up resistors inside the PCM that keep the signals at 5V nominally. See the posts after the initial one in this thread:
https://wranglertjforum.com/threads/crankshaft-camshaft-position-sensor-voltage.72437/
Knowing that, I no longer believe your PCM is the issue.
https://wranglertjforum.com/threads/crankshaft-camshaft-position-sensor-voltage.72437/
Knowing that, I no longer believe your PCM is the issue.
Thinking more about your situation, I think you need to go the 'scope route and look at the cam and crank signals to see if they're working properly. Going back to that error code, it's indicative of the cam signal being non-existent.