JeepForum.com - Reply to Topic
Thread: External voltage regulator or not Reply to Thread
Title:
Message:

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in










  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
01-26-2016 12:34 PM
Sloepoke Haven't posted in a while so to keep everyone from forgetting about me I'm updating even though I don't have much to tell . I contacted the company I purchased the PCM from & they said to send it back & they would test & repair it . Due to the winter storm we just had I didn't get it mailed out till yesterday . The weather is supposed to be pretty decent so I'm going to do some serious wire tracing & testing while I'm waiting to get it back & before I plug it in .
01-18-2016 12:46 PM
Sloepoke Due to the fact that my garage is too full to get the jeep in & it's 13 degrees outside I won't be working on it today .
01-17-2016 04:33 PM
streetglideok Not yet, other than a faulty PCM
01-17-2016 01:11 PM
Sloepoke streetglideok , I'll do that { probably tomorrow } then report back . If I don't get a short to ground on any of those wires is there a step 2 you have in mind at this time ?
01-17-2016 12:41 PM
streetglideok Unplug your pcm connectors, all of them, and unplug your injectors, all of them. Then check for a short to ground on every wire that goes from the injectors to pcm. If there is a short, then you might solder a new wire in from the pcm to the injector. Plug it all in and start it up.
01-17-2016 12:35 PM
Sloepoke I left the original pcm in the jeep when I installed the engine & had these problems . I installed the pcm from the wrecked jeep & the engine would start & run for a couple seconds then shut off . I started it 4 or 5 times then the pcm locked out & the engine wouldn't even turn over . I then read it has to be programmed to the vehicle or this would happen . There are places online that you can give your vin & such to & they will program a pcm & mail it to you . That is what I did & I still have the same problems I had with the original pcm . The place I bought the pcm from gave a lifetime warranty & said any future repairs would be free minus shipping so hopefully I can send it back & get it repaired if it fried .
I have read maybe I could have used the pcm from the wrecked jeep if I had swapped the ignition switch & immobilizer module . I guess I'm learning by trial & error .
01-17-2016 11:54 AM
02blue I'm really not qualified to help with this type of electrical stuff but have been following this thread as there is some good info here. Just curious, and maybe I missed it, but you say you tried a new PCM right. Same issue persisted. Did you try the PCM from the donor engine or a real new PCM. I'm assuming you initially left the original PCM in place when you swapped in the donor engine? If you haven't tried the donor PCM, may be worth a shot. No harm if you have it and who knows. I've seen stranger things with my 02.
01-17-2016 11:32 AM
Sloepoke I'll freely admit I'm all wet as this is my first problem of this sort with a vehicle . A little back history how I got into this mess . I bought this jeep from a friend & the engine had already been condemned due to bad compression . I ran a compression check to satisfy myself it was actually bad & it was . I then bought a wrecked jeep , same year model , same engine & low mileage & the wrecked jeep still run & drove & the engine ran fine in the wrecked jeep which had been hit in the side behind the drivers door .
I pulled the engine out of the wrecked jeep & installed all new expansion plugs , new rear main oil seal , new motor mounts , new spark plugs & a new torque converter seal in the transmission . I then installed the engine & ran into these other problems . Since the engine ran good with no apparent problems in the wrecked jeep & I'm sure I didn't damage anything in the removal & installation process I'm assuming the sensors & all are OK .
This leads me to believe this jeep had more than low compression issues . I drove this jeep about 40 miles home when I bought it & the engine ran like crap which wasn't unexpected . I found a compression gauge adapter still threaded into # 4 cylinder with a spark plug threaded into it & the electrode on the plug was mashed flat . This is the engine I replaced . I realize all this doesn't have much to do with my current problems but it shows the alternator & sensors & such seemed fine on the engine I installed .
I now believe this jeep had wiring or pcm problems in addition to low compression . As far as replacing the pcm to injector signal wire for # 4 injector , I had already considered it might be open or shorted . I used a noid light & it wouldn't flash on that injector connector. The power wire to that injector has battery power . After further testing I found the continuity on that signal wire to be good with both ends of it disconnected & it won't read to any of the other wires in its harness .
With all 4 pcm plugs disconnected the pin for # 4 injector signal wire reads to the pcm case / ground . I traced the signal wires for a couple other injectors & they don't read to the pcm case / ground . It appears I now have a constant ground on that pin internal to the pcm . I assume if I tried a noid light again it would light up without flashing but I haven't tried it . With 2 pcm's exhibiting the same problems with # 4 injector & the alternator connected no rev problem I can't help but think something , somewhere in the wiring harness is the problem . I will remove # 4 signal wire from the harness & hope I find a problem with it . I will also inspect the power wire to # 4 to make sure it isn't intermittently shorting to ground . Since # 4 injector signal pin in the pcm is giving a constant reading to ground , I imagine this pcm is fried . Sorry for such a long , rambling post .
01-17-2016 01:08 AM
Billwill
Quote:
Originally Posted by Sloepoke View Post
I have been all over the internet trying to find if there's a way to read the pcm pins with a meter . For example , If 12 volts is applied to pin 23 then pins 17 , 34 & 9 should read 12 volts . That is just a made up example . So far I've found nothing . I guess it's time to start stripping & inspecting harness .
You cannot really "apply" voltage to a pin unless you know what you are doing and are very careful. Your example above makes no sense...you can look at the circuit diagram and there is a section that shows the pinouts of the various connectors. Look at the pinouts for the 4 connectors on the PCM and you will see that your example makes no sense....C1 pins 29 and 30 pick up +12 volts for example.

You need to have the ignition ON or sometimes have the engine running, all plugs connected, then strap sewing needles or pins onto your meter leads so as to be able to piece the insulation on the wire that you need to read.

Then following the circuit diagram 8W-30-18 with your meter set to Ohms and the ignition OFF, pull the connector off injector #4...make sure you are counting the injectors properly...should have a Brown/Tan wire on it.

Then piece the Brown/Tan wire at the PCM connector C2 Pin11 with one of the meter leads and have the other meter lead to ground. You should read next to nothing on the meter ie. a couple of M Ohms...not a low reading such as 5 Ohms....wriggle this wire around while doing this. Then disconnect C2 from the PCM and repeat the process....you should get an infinite Ohm reading because the lead should be totally floating in the air.

Now plug the injector back in place and connector C2 back on the PCM.
Pull out the ASD Relay from its socket in the box under the hood.
Jumper pins 30 to 87 with a short piece of wire inside the ASD Relay socket...this is to simulate the ASD relay being energized as it would be if the engine was running.
With ignition ON, your meter set to DC Volts, the Black meter lead onto chassis or negative battery post, measure the voltage on the Brown/Tan wire with the red lead of the meter..should show +12 volts. Measure this at the injector #4 plug pin 2...should show +12 volts as the +12 volts should go through the fuel injector coil. Likewise pin 1 on the injector #4 plug...Pink/Gray wire....should show + 12 volts.

Repeate these action on one of the other fuel injectors and compare results with #4 injector.

Then with the jumper removed from the ASD Relay socket and relay back in place, engine running and the meter set to DC volts, check what you are reading on the Brown/Tan with the other meter lead on chassis....you are expecting this Brown/Tan wire to be at +12 volts with respect to ground most of the time and then for a very brief moment as the injector fires this wire should go to ground. It is difficult to see this brief action with a meter...you can try set your meter to AC volts, take the reading and compare with the other injectors.

If the PCM has blown Pin 11 on Connector C2 then you will get different results compared to the other injectors of course....you need to first do all your measurements with ignition OFF to see if you can find a fault on the injector #4 lead while moving the lead around....if you do not find a fault this way then you will probably blow up the next PCM you put in.

Hopefully you will find a a fault in the Brown/Tan wire in which case repair the fault before putting in a new PCM.

If you do not find a fault, what I would do is cut the Brown/Tan wire off a few inches from pin 11 on C2 connector at the PCM, cut off the other end of the Brown/Tan wire a few inches from the Pin 2 at the #4 connector...leave that wire hanging in mid air with insulation tape on both ends!

Then replace that wire with a brand new wire taking the shortest route as a temporary measure and insulate both ends with insulation tape and see if things now work with a either the original PCM in or a new PCM.

Have fun!!!
01-16-2016 03:39 PM
streetglideok
Quote:
Originally Posted by Sloepoke View Post
I have been all over the internet trying to find if there's a way to read the pcm pins with a meter . For example , If 12 volts is applied to pin 23 then pins 17 , 34 & 9 should read 12 volts . That is just a made up example . So far I've found nothing . I guess it's time to start stripping & inspecting harness .
Not sure I follow you. If you view the diagrams, the wires going to fuses will be battery power, or switched on battery power. If they go to ground, then its ground.
01-16-2016 09:22 AM
Sloepoke I have been all over the internet trying to find if there's a way to read the pcm pins with a meter . For example , If 12 volts is applied to pin 23 then pins 17 , 34 & 9 should read 12 volts . That is just a made up example . So far I've found nothing . I guess it's time to start stripping & inspecting harness .
01-16-2016 01:40 AM
Billwill
Quote:
Originally Posted by Sloepoke View Post
I found what seems to me to be a problem . Since it's always a P0204 code which relates to # 4 injector & no codes for any other injector I concentrated on the wires for # 4 . With an ohm meter I got a constant reading to ground on the pcm ground signal wire with the injector unplugged . I checked a couple other injector ground signal wires & didn't get any reading to ground . I found that wire at the pcm & made a small bare spot in the insulation close to the pcm connector . Checked continuity from the bare spot to injector connector & continuity was good .
I unplugged the pcm connector that wire was in & reading from the bare spot I made to the connector terminals I found which pin in the pcm that wire goes to . That pin in the pcm reads to ground . I traced another injector ground signal wire to its pin in the pcm & got no reading . With all pcm connectors unplugged the pin for # 4 still reads to ground & pins for other injectors doesn't .
Backing up just a little , the ground signal wire for # 4 no longer read to ground after being unplugged from the pcm . All this leads me to believe that there is a pcm problem . What I find weird about all this is that the original pcm was doing the exact same thing . Just came in for a cup of java & am going back out & see if I can get any reading from # 4 injector ground signal wire to power or if it maybe has stray voltage on it . Will post again a little later .
The problem with shorted or grounded wires is that they can blow that part of the PCM up. You replace the PCM with a new one and that same part of the new one gets blown up.

So you have to find the problem in the wiring to injector #4 first before once again fitting a new PCM and ending up with a pile of PCMs.

I personally would completely cut off both the leads going to injector #4 and leave them floating. Then fit a pair of new wires from the injector #4 connector back to the PCM pin for the ground signal and to the splice in the harness where all the injectors get their +12 volts from. Also check #4 injector again..maybe this also got blown up!

Then try a new...hopefully last....PCM with your new pair of wire attached.
01-14-2016 01:27 PM
Sloepoke I found what seems to me to be a problem . Since it's always a P0204 code which relates to # 4 injector & no codes for any other injector I concentrated on the wires for # 4 . With an ohm meter I got a constant reading to ground on the pcm ground signal wire with the injector unplugged . I checked a couple other injector ground signal wires & didn't get any reading to ground . I found that wire at the pcm & made a small bare spot in the insulation close to the pcm connector . Checked continuity from the bare spot to injector connector & continuity was good .
I unplugged the pcm connector that wire was in & reading from the bare spot I made to the connector terminals I found which pin in the pcm that wire goes to . That pin in the pcm reads to ground . I traced another injector ground signal wire to its pin in the pcm & got no reading . With all pcm connectors unplugged the pin for # 4 still reads to ground & pins for other injectors doesn't .
Backing up just a little , the ground signal wire for # 4 no longer read to ground after being unplugged from the pcm . All this leads me to believe that there is a pcm problem . What I find weird about all this is that the original pcm was doing the exact same thing . Just came in for a cup of java & am going back out & see if I can get any reading from # 4 injector ground signal wire to power or if it maybe has stray voltage on it . Will post again a little later .
01-13-2016 07:15 PM
streetglideok There are known issues about the tps not working correctly, and generating "noise" and triggering injector faults. It takes a lab scope to see the noise, not something many have, not even techs. I'm not convinced it's even an issue in your case, as it seems related to the alternator.
eta: My PM box is full right now, I know in case anyone tries to message me. Will get around to upgrading my account later this month.
01-13-2016 01:35 PM
Sloepoke streetglideok , I was really hoping you'd take an interest & post on this thread . I have read numerous other threads you have posted in & you seem very knowledgeable . My next step was to disconnect , clean & reinstall every ground I can find . If that doesn't fix it I'll proceed to the other things you mentioned . Billwill & others that are making suggestions , I really appreciate the help so keep it coming , sooner or later we'll solve this problem .
It's supposed to warm up in the next day or two & I'll get back on it then & then post again .
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

 
For the best viewing experience please update your browser to Google Chrome