Tomahawked Posted March 23, 2009 Share Posted March 23, 2009 This problem definately gets technical, especially long as it took me to find the culprit. Here is the scenerio. I had acquired a 90 Cherokee for all donor parts to build my 88 Comanche. Changed from a standard to automatic also. I used the complete engine harness back to firewall from Cherokee. Got rid of that big connector above brake booster. I wired in the extra pieces to dash harness needed for the automatic that replaced the old 5 speed. Had both harnesses layed out together tracing wires hoping to get everything correct. Basically stripped the 90 dash harness and added what was needed to the 88 harness. Lots or splices and solder joints to repair all damaged pieces. Nothing staked or crimped for any repairs. So I basically changed the complete motor, transmission, transfercase and D30 front axle. So converted to 4wd just like most people. Everything installed and motor ran. I did not have an alternator from any of the parts. So grabbed one from boneyard. Installed it and was reading 14.4 volts with meter. As I had time over the next couple of months finished all of the loose ends. Everything was working, so I thought except for volt and oil pressure gauge. I took in on its maiden voyage last Friday for a 120 mile round trip, and got the inspection sticker while out. After dark, I drove back and started having the usual issues of surging power, loss of lights that ended up draining the battery dead. Borrowed another battery and drove the other 30 miles remaining back. Checked the junkyard alternator and was not putting out voltage. SInce it was used and bearings were noisy I replaced it with a brand new one but still nothing. I started troubleshooting and found nothing that I knew to be wrong. Left it alone and started fresh the next morining. Rechecked everything, reinstalled then alternator was charging and reading 14.2 volts with all of the lights on or off. All was good. I finished up some other details and was ready to call it fixed. Later in the day when finished I checked voltage one last time and nothing. Removed alternator twice kept checking and could not find out why it would not charge. So ask questions and see if you can figure out what I finally found wrong. This is one reason why I would never do auto repair for a living and won't pay someone else to work on any vehicles of mine. Think hard and give it your best shot. I learned a lot and will probably never run into this problem again. Link to comment Share on other sites More sharing options...
jtdesigns Posted March 23, 2009 Share Posted March 23, 2009 Fusible link? or maybe the wire that comes from the ecu to turn the voltage regulator on?? Link to comment Share on other sites More sharing options...
MiNi Beast Posted March 23, 2009 Share Posted March 23, 2009 bad fuse in the alt Link to comment Share on other sites More sharing options...
jtdesigns Posted March 23, 2009 Share Posted March 23, 2009 Low blinker fluid. Link to comment Share on other sites More sharing options...
MiNi Beast Posted March 23, 2009 Share Posted March 23, 2009 Low blinker fluid. Hey I'm serious. :no: Link to comment Share on other sites More sharing options...
jtdesigns Posted March 23, 2009 Share Posted March 23, 2009 I think it might have something to do with the volt gauge.. Remembering the same problem I faced with an S-10 not having the cluster in for a day or two.. Something about the alt used the gauge cluster to know when to charge.. or could be a bad bulb? Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted March 23, 2009 Share Posted March 23, 2009 swapped BATT and ignition on wire harness to multiswitch/ignition switch on lower column? having the ignition "on" would cause the acc to be "dead" but cause a common drain- maybe eat a battery in a couple of hours/maybe not. It`d still start and run... I guess you could have done the same thing on the ignition box under the hood- it sounds like a common drain off a wire that should be dead with ignition off.... make me feel dumb. :doh: Link to comment Share on other sites More sharing options...
Tomahawked Posted March 24, 2009 Author Share Posted March 24, 2009 The problem was not a drain. It wasnt charging. It showed charging voltage once then later only actual battery voltage. I had voltage from switch RUN to alternator. Tried everything I knew and nothing would make any difference. What was odd is the 2 wire connector with a DVOM showed 12 volts across both wires. Even checking off each battery cable confirmed this. When engine running it had voltage across the wires. This didnt make sense, because what showed to be the ground wire should have been going thru the coil on volt meter. Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted March 24, 2009 Share Posted March 24, 2009 This is why I like to call it "bench guessing". Behind a computer screen, without the actual vehicle in your hands, your basicly down to getting as much information as possible, and breaking it down to a solution. I may have got it wrong, but what I used led me to my guess. "reinstalled then alternator was charging and reading 14.2 volts with all of the lights on or off. All was good. I finished up some other details and was ready to call it fixed. Later in the day when finished I checked voltage one last time and nothing" to me, what you wrote screams a voltage drain. If the alternator was charging the battery- you shut it off, and came back later, and the battery had no voltage. Link to comment Share on other sites More sharing options...
Tomahawked Posted March 25, 2009 Author Share Posted March 25, 2009 Sorry about the slight misinformation. The nothing I wrote was not a dead battery but the alternator not putting out. I gave up on trying to get the alternator going for the the moment. Later I started all over again. After rechecking the usual, I tore out the instrument panel and decided to focus on why the two gauges were not functioning. Since only two little screws hold gauge, I removed volt meter to check if it worked. Hooked to battery and worked fine. I checked across the connection on back of mylar circiut board and nothing. Followed back to the connector and with key on it had voltage. I noticed the copper strip powered both oil pressure and volt gauge. At least I found a common denominator between them. I scratched thru the strip at intervals along path to first gauge. All the way to the oil gauge there was continuity, but not at the gauge itself. I removed the connection screw and there was the problem. A tiny crack across copper strip where the washer had cut thru. So I just loosened the screw and pushed washer over the break and tightened it back. Now everything is working, battery is fully charged and I am a happy camper again. Its suprising how such a small imperfection could cause major problems. I realize now why the alternator was probably missing on the donor Cherokee. Someone had removed it thinking was bad. I swapped most of the Cherokee parts over to Comanche since all of the 4wd lights and things that were different. It also reaffirms how thorough someone needs to be when troubleshooting something without knowing exactly what is causing the problem. Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted March 25, 2009 Share Posted March 25, 2009 you are hearby nominated "master dashboad electric fixit guru", with all the pride and know how that comes with it. hey, no one ever said it`d be easy- just fun. Because if it isnt fun, its work....an no one likes work. ;) theres a "bypass" hidden somewhere on the back of that board, that once cut- shows the true voltage of the system instead of "downstream" voltage- or "whats left over" volts. I still can't find that write up- Stu over at NAXJA did it...and it vanished. Link to comment Share on other sites More sharing options...
MiNi Beast Posted March 31, 2009 Share Posted March 31, 2009 yeah I would have swapped to all new wiring and dash setup from a good donor before all that. But I'm an impatient bastard. So thumbs to you for that diagnostic find! :thumbsup: Link to comment Share on other sites More sharing options...
xflowdaboi352 Posted April 1, 2009 Share Posted April 1, 2009 its ur comuter value u need a new one. Link to comment Share on other sites More sharing options...
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