Originally Posted by RUBI 4 MY MRS
I’m not sure how those are wired in but seriously doubt they can deactivate the 5v outputs. If the immobilizer was somehow designed to block the 5v outputs you would find that if you tried to start it with the immobilizer still set (on) besides not starting, none of the gauges would respond. Most systems either cut the power to the starter so turning the key to start gets nothing, only silence, or they cut power to the ignition & you get crank, no start. The later SKIM option would allow start for about 3 seconds then die. That would work for about 3 starts then just give you crank, no start. That is the 3 most common types. How did yours work? And what is happening now? Crank, no start?
The best indication you have no 5v output from the PCM is when you turn the key to on (not to start) & none of the gauges move. Especially noticeable would be no volt or fuel gauge movement (as noted above).
Have you actually checked the 2 5v outputs to verify whether you are getting 5v?
I see you have a 1997, 2.5L. For some unknown reason most of the failed 5v output PCMs have been in that year & engine. I have seen some others & some of those have been caused by shorted sensors or their wiring so that is always a possibility. Especially if there is some (but lower than 5) voltage showing when checked.
I did a quick search of that immobilizer but could not find much info as to how it functions so any info you have on that might be helpful too.
Dear RUBI 4 MY MRS,
First of all thank you for your input into the topic i have opened couple weeks back here https://www.wranglerforum.com/#/topics/2375463
i did lots of checkS using the multimeter into the PCM and on the wires as well. I have reached to the conclusion very easy, thanks to you, that i did not have 5v output whatsoever. I was actually having 0.8v and 0.6v on them if i recall properly, any way it was 0.x V .I believed it was the PCM faulty because of that burn i found inside of it when i opened it. I told you about that and also i have attached a photo of it in the above mentioned post. That burn as i was telling you earlier goes to pin A22 into the PCM black connnector and according to the service manual it is going to fuse B + and into circuits A3and A14 which i have followed all the way to the light switch and i couldn't find an answer why it burnt the PCM in the first place..it still is a mistery to me now.
My TJ, after i have repaired the board was cranking with no start. No gas wasgoing to the injectors.
With no 5v on theboard i have externally supplied 5v and fired the engine and then i instantly got gas at the injectors and the car was starting but could not idle. Was shutting down immediately. If i cranked with the foot all the way on gas it ran for 2 seconds then stopped.
I have then assumed that there was something wrong with the ASD relay. Although the relay itself was functioning i have thought that there was something wrong with its wiring, so i have bypassed it. I started the engine, it was not working while idling but at 3000rpm revs it was running great and did not shut down after 2 secs as it used to do, it ran for good 20 sec and then smoke came out of the PCM. A part of the board was fried and melted and i checked a bit and found out that it was in charge of controlling the ignition coil.
Now with no PCM available and one on the way, ordered from flagship one, who by the way they say that they are working diligently to program it for five days now, i have recaped all issues i had, and according to some of the posts you shared with me-thank you- and other ones i have read online and youtube videos watched i have reached these conclusions:
1- PCM part which is controlling the step by step engine inside the AIC is either deffective or the imobiliser is shutting down the engine( The wiring was good and the AIC motor is giving me 56ohms resistence on both circuits inside it and no short circuit inbetween); besides this, the imobiliser has two wires going to the CCD bus so it can as well tell the PCM what to do
2- the ignition coil might send high voltage back to the PCM causing it to fry
3- the imobiliser is defective because no matter what button i press on it the car reacts the same :gauges not working, engine cranking and not starting. Because i have managed to start the engine only by bypassing the asd relay i am under the impression that the imobiliser is the problem. The other issue is that i do not understand why the pcm was fried in the first place and the second time as well !