2000 Cherokee No Bus
06-24-2016, 08:36 AM
#16
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Year: 1999
Model: Cherokee
Engine: 4.0
Ok, I used mini paper clips as test probes so as not to damage the pin cavities, last night after I last replied to this thread I put one in cav24 of tcm, and on in cav 5 of dlc, tcm ground and pcm ground, when I touched a wire to the two it sent off a spark and blackend that arc spot on the tcm paper clip, so I attempted again using dlc pin 4 instead, got the same spark, so I did it again on dlc pin 4, except this time I held it there for maybe 3 seconds, the paperclip turned red hot, melted in the middle, and when I pulled the wire off, the paper clip end fell and cooled, turning it from a straigh paper clip to a 90, I thought that pcm and tcm and plain ground share the same grounds, something must be feeding voltage into tcm ground correct? Tcm cav24 to gas pedal stud showed 150 ohms, way more than the 5 ohm threshold.
Engine swapped in is also from a 2000, has a coil rail.
I can check grounds later tonight, for a large part of the day today I will be at the local hospital getting my thyroids checked out.
Engine swapped in is also from a 2000, has a coil rail.
I can check grounds later tonight, for a large part of the day today I will be at the local hospital getting my thyroids checked out.
You better STOP fooling around with the ground at 24. That ground wire is only 18 gauge and is not fused, and by the looks of it you are pulling full battery capacity through it. If not already happened, that ground wire will melt and you'll end up running a new ground wire from G101 to pin cav 24 of the TCM connector.
Also, the PCM is probably smoked by now.
For the time being, I think you should remove both of the battery connectors while you visually check the wire hook-ups in the engine bay. Something got hooked up wrong or was damaged (short to ground) when changing the engine.
06-24-2016, 11:45 AM
#17
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Ok, I have 2-3 other exact same pcms to try If I fry this one, not that I wanna have to go that route, but Its always there, what about the 150 ohms from cav 24 to the gas pedal studs?
The ground to ground of dlc to tcm has continuity, so why did it spark?
I will look tonight at connectors and grounds I guess, maybe swap the pcm.
The ground to ground of dlc to tcm has continuity, so why did it spark?
I will look tonight at connectors and grounds I guess, maybe swap the pcm.
06-24-2016, 11:59 AM
#18
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Year: 1999
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Ok, I have 2-3 other exact same pcms to try If I fry this one, not that I wanna have to go that route, but Its always there, what about the 150 ohms from cav 24 to the gas pedal studs?
The ground to ground of dlc to tcm has continuity, so why did it spark?
I will look tonight at connectors and grounds I guess, maybe swap the pcm.
The ground to ground of dlc to tcm has continuity, so why did it spark?
I will look tonight at connectors and grounds I guess, maybe swap the pcm.
Rectify the wiring fault that's causing battery voltage to leak in to the ground circuit before doing anything else.
06-24-2016, 04:20 PM
#20
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Year: 1999
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Ok, I have 2-3 other exact same pcms to try If I fry this one, not that I wanna have to go that route, but Its always there, what about the 150 ohms from cav 24 to the gas pedal studs?
The ground to ground of dlc to tcm has continuity, so why did it spark?
I will look tonight at connectors and grounds I guess, maybe swap the pcm.
The ground to ground of dlc to tcm has continuity, so why did it spark?
I will look tonight at connectors and grounds I guess, maybe swap the pcm.
Going from 24 to the gas pedal you are going through the chassis to the battery negative post via ground G100 (see pic). Going from 24 to 4 or 5 on the DLC you are going to the engine at G102 (see pic) then to G101, then to the battery negative post.
In that you re seeing 150 Ohms using the gas pedal it tells me there is high resistance in the G100 path. Continuity from 24 to DLC 4/5 tells me that path is good.
The high resistance through the G100 path tells me that that connection is probably corroded and needs to be disassembled and scrubbed up.
Normally, folks that neglect G100 fall back on the braided radio noise suppression strap from the fire wall to the engine as the engine to chassis ground. That's not what its for but is the fail-safe ground path if G100 is bad.
G100 should be addressed.
G100:
.
Firewall noise suppression strap:
.
G102:
06-25-2016, 10:04 AM
#22
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Awesome, the batt. Direct to fender ground is a little rusted, I have cleanwd the strap grounds, but Im done guessing, I am going to take every batt, engine, chassis ground, It really would not suprise me if this whole problem has been caused by me overlooking something I thought was "good enough", I really do know my way around cherokees, just not so much specific electronics functions, I have 2 other xjs and never had this serious of an electrical problem.
06-25-2016, 10:47 AM
#23
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Year: 1999
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You may snap the head off the G100 bolt trying to get it out but it needs to be addressed.
Some XJ's have a M8-1.25 x 20 mm Bolt, some have a .250 sheet metal screw.
If you snap the head off pull the right front wheel and remove the plastic liner to get at the bolt stub. Use a pipe wrench or vice grips to remove the stub.
Recommend using Ox-Gard or NOALOX at all ground ring terminal connections. Can be found at Home Depot or Lowes.
.
Some XJ's have a M8-1.25 x 20 mm Bolt, some have a .250 sheet metal screw.
If you snap the head off pull the right front wheel and remove the plastic liner to get at the bolt stub. Use a pipe wrench or vice grips to remove the stub.
Recommend using Ox-Gard or NOALOX at all ground ring terminal connections. Can be found at Home Depot or Lowes.
.
06-25-2016, 11:14 AM
#24
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Okay, will do, may not get done tonight because we have a church cookout and am in the midst of installing an ac unit there today, I appreciate the help and effort you are taking to help someone you have never met solve problems that otherwise would cost a lot of money to be fixed professionally, I owe you one
06-29-2016, 11:28 AM
#29
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See my pic.
Looks like bubba used a 10-12 Gauge wire (yellow) ring terminal for an 8 gauge cable. Not good.
Unwrap that connection and see what he did. An 8 gauge cable needs an 8 gauge cable ring terminal.
I think you should at least try and remove the original G100 bolt and see if you can get an 8 gauge ring terminal with a 5/16" stud hole and redo that connection, then relocate the cable to its original spot, using a new M8-1.25x20-25mm bolt.
Looks like bubba used a 10-12 Gauge wire (yellow) ring terminal for an 8 gauge cable. Not good.
Unwrap that connection and see what he did. An 8 gauge cable needs an 8 gauge cable ring terminal.
I think you should at least try and remove the original G100 bolt and see if you can get an 8 gauge ring terminal with a 5/16" stud hole and redo that connection, then relocate the cable to its original spot, using a new M8-1.25x20-25mm bolt.