Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I think you didnt probe it right see photo this is a bottom view of relay diagram just flip the outer two of the group of three for the fuse box side to test powers
Hardtopdr2 wrote: I think you didnt probe it right see photo this is a bottom view of relay diagram just flip the outer two of the group of three for the fuse box side to test powers
ok thank you. If thats the case light comes on to 86 an 85 reads .002
Monde wrote: You should have power on pin 85 ( Test light to ground an tip on pin 85) and control on pun 86 (Test light to power and tip on pin 86). Have you tried another fuel source?
i have used starting fluid and it fires for a second.
Monde wrote: You should have power on pin 85 ( Test light to ground an tip on pin 85) and control on pun 86 (Test light to power and tip on pin 86). Have you tried another fuel source?
i have used starting fluid and it fires for a second. Is this correct?
Monde wrote: Since you don't have a 5v reference, and pcm powers and grounds seem not to be an issue, what I would do next is to start unplugging sensors to see if you will find one that is shorted pulling the 5v ref down.
Will do. Do i pull them 1 by 1 and leave them unplugged or do plug it back in after i check 1? Also i got a can of starting fluid today shot it in air intake and almost seemed like it wanted to go for a second but nothing. I tried it a few times after and just cranks. I just wanted to verify for myself. I was going off what the tow truck guy said.
Monde wrote: You can leave them unplugged or plugged them back in. You just have to monitor the 5v ref at one of the sensors like tps, maf, cam crank and so on. No need to unplug coolant sensor, any thermistors.
Do you have access to a scan tool that can read other modules besides the pcm? If so, can you communicate with other modules?
I checked tpm, maf, cam, crank, air intake, thermostat and every other thing i could find i thought was a sensor no 5v reference anywhere. Unfortunately i don't have that kind of equipment.
Monde wrote: Your Jeep is not equipped with a MAF. The sensors that you need to unplug are CRANK, CAM( inside of distributor) TPS, MAP, Engine oil pressure sensor. The vehicle speed sensor seems to have a different 5v ref. I may be wrong. You can unplug it as well. Just make sure you monitor one of them. Make sure the one you monitor remains plugged in. Hopefully, you can do that.
Sorry about that it was the MAP sensor. Pics of sensors i pulled. I am having trouble pulling the oil pressure sensor.
Monde wrote: Your Jeep is not equipped with a MAF. The sensors that you need to unplug are CRANK, CAM( inside of distributor) TPS, MAP, Engine oil pressure sensor. The vehicle speed sensor seems to have a different 5v ref. I may be wrong. You can unplug it as well. Just make sure you monitor one of them. Make sure the one you monitor remains plugged in. Hopefully, you can do that.
Sorry about that it was the MAP sensor. Pics of sensors i pulled. I am having trouble pulling the oil pressure sensor..
***update*** so i was able to pull oil pressure sensor and still no 5v reference.
Monde wrote: Can you access pin A17 ( orange wire) at the pcm. Backprobe pin A17 at the Pcm, hook voltmeter to ground and tip to pin, see if you have 5v or close to 5v there. You can do the same for pin B31(violet/ Orange wire.
You don't have spark, right?
I back probed A17 and got .628. Back probed B31 and got .437. No spark from what i see i put a screwdriver in the boot wrapped with copper wire and placed the other end about 1/8 of an inch away from engine block and didn't see any spark.
Monde wrote: So with the key in the START or RUN position, you back probed A17 and B31 and you get.628 and.437v. This suggests that either one of the sensors or its circuitry is shorted or the pcm is not providing the 5v ref. If the 5v ref were open, you would get 5 or close to 5v at pin A7 and B31 unless you have a connector issue. With good powers and good grounds at the pcm, it should be able to provide the 5v ref to the sensors, but is not. We might be dealing with a pcm problem. Before we condemn the pcm, let's unplug the connector and touch A17 and B31 pins with voltmeter positive lead and negative lead to ground with key in the RUN or START position to look for the 5v ref. Also, you can put the voltmeter in ohm setting, unplug the connector, set the meter to the highest ohm scale, front probe pin A17 or B31 with black meter lead to ground( battery disconnected), acceptable reading OL. Make sure you don't damage the connector. Back probing it would be better, but slightly touching it is fine.A helper is needed because you need the vehicle in START or RUN position.
If everything fails, we might need to start looking at inputs ( CAM ann CRANK sensors, or antitheft issue)
A17 is at 1.461 B31 is at .156 and ohm reading at A17 was 3.856 and continuously rising B31 was at 185.4.
Monde wrote: So, when you put the tip of the red lead to pins A17 and B31 at the pcm itself(connector unplugged) and the other lead to ground with key in the START or RUN position, you get 1.461v and .156v? IF SO,, we can be sure that the pcm is not sending the 5v ref out. I don't think inputs nor anti theft issue will keep the pcm from sending the 5v ref out. We may need to replace the pcm. Some people would experiment with a 5v battery.
I really can't provide any more assistance. Hopefully, other people will assist. If for any reasons you end up taking the car to a shop, keep us informed of the finding.
You can also have the car scanned with a scanner that can reads other modules besides the pcm. They might have communication codes.
Thank you for everything you have been more then helpful. Im not great with electrical issues hopefully i did everything correctly. I definitely keep you posted on what i come up with.
Dukeh wrote: Did we verify power in and no power out from pcm?
The aftermarket wiring diagram posted earlier was for the XJ, not the WJ, and the wiring colors weren't correct. Probably best to re-check powers and grounds using the OE diagrams Monde posted.
Monde wrote: Can you verify to see if the diagram I posted is correct? That would help us greatly if you could. We will get to the bottom of it once we know.
I will check everything out tomorrow. Thank you guys.
