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94 dodge truck wont start
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Discretesignals
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May 12, 2012, 4:05 PM
Post #26 of 113
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Re: 94 dodge truck wont start
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Just making sure, but you did make those measurements on the back of the connector with it still plugged into the PCM?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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r.foust
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May 13, 2012, 9:47 AM
Post #27 of 113
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Re: 94 dodge truck wont start
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good morning descrete so how was ur cookout on the grill lastnight ? we got lucky with ares and the rain held of other a few sprinkles .
well i got up and checked on the readings with each sensor unpluged and here is what i got and this checking and double checking and evening check for the third time even the only thing was each time i checked it i would get different readings but it was within a number or two .
TPS: .20 average
Map sensor : .17
Cam sensor : .33
Crank sensor : .40
Speed sensor : .13
the only thing is i left computer unpluged lastnight and i also checked the # 9 pin and this morning i dont have the 12 volts at the pin like i did yesterday
thanks Ron
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Discretesignals
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May 13, 2012, 5:42 PM
Post #28 of 113
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Re: 94 dodge truck wont start
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I hope that you had a great cookout also. I did end up grilling up some fresh salmon. I could eat that stuff everyday..tastes good with a little BBQ sauce on it.
I just want to make sure that you made those measurements with the PCM connector plugged in and your meter backprobed because you want the circuits loaded when doing voltage drop testing.
Seeing how the 8 volts didn't come back after you unplugged all those sensors indicates you don't have a sensor shorting out the 8 or 5 volt power supplies in the PCM. The only thing that is left is the wiring for the 8 and 5 volt power supplies. You have a couple of options.
1. You can physically cut the wire for the 8 and 5 volt circuits and see if your voltage comes back. If it does, that indicates an short to ground in the wiring somewhere. If you do cut the wire, make sure you cut it several inches from the PCM connector so you can solder and heat shrink the wires back together.
2. You can unplug the connector and ohm out those circuits to see if they are shorted to ground with all the sensors still unplugged. I suggest doing this just in case the short to ground fried the power supplies. You don't want it to happen to another PCM if that is the case. The PCM is supposed to be able to protect itself from shorts on the power supplies, but there is no guarantee on that.
If you do find that your supply voltages come back you just have to find out where the wiring is shorting out.
If it doesn't come back, your PCM is highly suspected of being the culprit.
Can't quite connect the timing chain job to a dead PCM, but maybe a coincidence. I guess time will tell.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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r.foust
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May 13, 2012, 6:28 PM
Post #29 of 113
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Re: 94 dodge truck wont start
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ha jon glad to hear u had a good cookout as well
jon when i did the test of unplugging each of the 4 sensors you suggested i had main connecter unplugged from the PCM of each check of the sensors. im not good on eletrical troubleshooting or know much on how to actually check it. but the only way to learn is hands on i guess whats a better way lol.
2. You can unplug the connector and ohm out those circuits to see if they are shorted to ground with all the sensors still unplugged. I suggest doing this just in case the short to ground fried the power supplies. You don't want it to happen to another PCM if that is the case. The PCM is supposed to be able to protect itself from shorts on the power supplies, but there is no guarantee on that.
for me to do this step your talking about above i dont quit follow what u r say on how to check for a short in line someplace because i would rather not cut the wire at the connect it i dont really half to you know what i mean
jon before i actually found and figured out that it jumped time i had sent PCM out through local parts store O'reillys and had it checked out and from what the people at the part store said that they went head and rebuilt my PCM but how true that is i dont know because it was all cleaned up when it came back from Pa. then i went to one of them places on the net that u pay for a persons advise and because putting computer in truck didnt start i had 2 different people tell to change my crank and my cam sensor so i did and that didnt take care of it not starting either so then i started moving plug wires around because with old distibutor they had the # 1 plug wire on # 7 of distributor so when i put marks to factory spec and put new plugs,wires.distributor,and rotor and tride starting it and it would start and finally figured out i wasnt keeping my 12 volts to the coil or getting back when i cranking motor over
thanks Ron
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Discretesignals
Ultimate Carjunky
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May 14, 2012, 5:09 AM
Post #30 of 113
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Re: 94 dodge truck wont start
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It's important that the PCM connector is plugged in when making those checks. Not still sure if that is exactly what you did. You have to back probe those circuits at the PCM connector. The reason you want to backprobe is because it keeps the circuit connected and you don't bend the terminal open when shoving a lead down it
What your supposed to see on PIN 7 is 8 volts and PIN 6 is 5 volts with key on.
If you have no or low voltages on those two circuits that means you either have something shorting those circuits to ground or a bad power supply in the PCM. That is why I had you unplug those sensors that use those power supply voltages. If one of those sensors was shorted out, you would see your power supply voltages come back up.
Since you didn't see that voltage come back up, that leaves two things. (1) the wiring (2) the PCM. If you disconnect/ clip the wiring at the connector and your power supply voltages come back that means you have a short in the wiring. If not, bad power supplies in the PCM.
PCM has an internal voltage regulator that takes the battery voltage it gets to step it down to those 8 and 5 volts for sensor power. WIthout those voltages, engine won't run.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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r.foust
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May 14, 2012, 5:48 PM
Post #31 of 113
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Re: 94 dodge truck wont start
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ha jon i just got home from work and got your message from this morning its 6:30 pm my time now. to answer you no i had the main connector going to the computer unplugged when i dont all the volts yesterday morning with unplugging each sensor. and checking the volts at pin #7 i dont have a T pin like in the picture you sent but i do have a paper clip more or less the same ideal and princable as the pin when i get done eating i will go and recheck the volt readings with connector plugged into the computer and unplug sensors one at a time again like before
thanks Ron
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r.foust
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May 14, 2012, 7:19 PM
Post #32 of 113
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Re: 94 dodge truck wont start
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jon i went and plugged the connector back into the PMC for some reason im not showing 12 volts to the # 9 pin now
with a paper clip stuck on the wire side of the connector im still showing 0.00 and when i unplugged each sensor i got no change in volts
. but seeing im not getting 12 volts at the #9 pin im guessing that is why im not getting a reading on # 7 pin.
i stuck the #6 pin and i should .24 on meter and when i unplugged map sensor it went to .26 and then with map sensor and TPS unplugged it went to .28 and when i plugged them both back in it dropped back down to .24
thanks Ron
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Discretesignals
Ultimate Carjunky
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May 15, 2012, 5:09 AM
Post #33 of 113
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Re: 94 dodge truck wont start
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You definitely need that 12 volt power feed on pin 9 light green/black with the ignition turned on. Make sure that your back probe is making connection when you slide it into the back of the connector cavity.
If you are certain you are missing your feed, just for conformation you can run a fused jumper wire from the battery positive to your back probe on pin 9 with the ignition on. See if your 5 and 8 volts comes back.
Inspect fuse number 9 10 amp.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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r.foust
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May 15, 2012, 7:18 PM
Post #34 of 113
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Re: 94 dodge truck wont start
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ichecked the #9 10 amp fuse and it was good will half to wait until this weekend before i can run inline fuse jumper from the battery ok
have question though seeing i lost the 12 volts at the # 7 pin could that be a problem with my ignition switch
thanks Ron
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Discretesignals
Ultimate Carjunky
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May 15, 2012, 7:28 PM
Post #35 of 113
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Re: 94 dodge truck wont start
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PIN 9 light green/black wire is the ignition switch feed and supposed to have around battery voltage with key on.
PIN 7 orange is your 8 volt power supply
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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r.foust
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May 16, 2012, 4:22 AM
Post #36 of 113
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Re: 94 dodge truck wont start
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hi jon ok i understand what you are saying about the # 9 pin being the ignition wire when the key is on and seeing since sunday i lost my power to that pin and it is part of the ignition switch that is why i asked if it could be the switch that went bad seeing when i checked the # 9 fuse as you said and it is good.
i will half to go to the part store to get me a inline fuse and some wire so i can make the jumper wire as u suggested to put power to that pin # 9 so i can see if i get the voltage back at pin #7 when i unplug the sensors again one at a time to check for a short within the main harness someplace
thanks Ron
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r.foust
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May 19, 2012, 1:42 PM
Post #37 of 113
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hi joh how have u been and hope u r having a nice and enjoyable weeked bud
well i made the jumper wire and went and got me some t-pins and with just the key on i dont have the 12 volts at # 9 pin still
i hooked the jumper wire to the battiery and i checked pin #7 and i have the 8 volts at that pin and i have 5 volts at pin #6
also when i hooked the jumper wire up the high pich wining noise from computer came back and with the key on i dont because with just the key im not getting 12 volts to the computer.
i hope i am explaining things well enough for to understand what i trying to say
thanks Ron
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Discretesignals
Ultimate Carjunky
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May 19, 2012, 2:09 PM
Post #38 of 113
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Hey Ron, just laying back today relaxing. Later I'll be wandering around the house with a paint brush...lol
Just out of curiosity, with the jumper hooked up, will the engine start?
Yep, you gotta find out where that power for pin #9 is being lost. What is the voltage at fuse 9 with the ignition on? Make sure your PCM connector and fuse is plugged in, so we can see if there is a drop in the circuit.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 19, 2012, 2:10 PM)
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r.foust
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May 19, 2012, 3:32 PM
Post #39 of 113
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hi jon ok i just check the volts at the fuse #9 and it is 0.00 jon and this with and with out jumper wire connected and i have juice at the rest of the fuses with out the jumper wire connected
i tried to start the truck with jumper wire connected and no it wont start with jumper wire
thanks Ron
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Discretesignals
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May 19, 2012, 3:47 PM
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Re: 94 dodge truck wont start
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Do you have power on fuses 10,11, and 12 with the ignition turned on?
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r.foust
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May 19, 2012, 8:48 PM
Post #41 of 113
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yes jon i have power to # 10 11 12 fuses with key on because i checked all the fuse in the panel and the only one im not showing any power to is my # 9 fuse jon
thanks Ron
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Discretesignals
Ultimate Carjunky
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May 20, 2012, 6:01 AM
Post #42 of 113
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Your going to have to remove the fuse panel, so you can look at the back of it. Check for corrosion or open bus bar feeding fuse 9.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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r.foust
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May 20, 2012, 6:34 AM
Post #43 of 113
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good morning jon ! arent we just full of good news this morning lol because taking fuse pannel out dont sound like much fun bud but ok
i still have a question though bud yesterday when i hooked up the jumper wire to the #9 pin can u tell me what the high pitch noise i am getting from the PCM
thanks Ron
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Discretesignals
Ultimate Carjunky
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May 20, 2012, 6:49 AM
Post #44 of 113
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To be honest, I don't know why it would make a high pitched noise like that. I'd figure we make sure the computer is getting everything it needs and then make sure it is sending out the right outputs.
I suspect there is a problem on the back of the fuse panel because fuses 10,11, and 12 get power from the same circuit as fuse 9 when you have the ignition on or in start. Since the panel is under the dash, it does look like a pain.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 20, 2012, 6:56 AM)
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r.foust
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May 20, 2012, 7:02 AM
Post #45 of 113
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yes it is under the dash on the side facing the drivers door but i already have the panels dropped so im alreadu part of the way there lol.
once i drop the fuse panel and start inspecting it what am i looking for in perticulor of what could be wrong
thanks Ron
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Discretesignals
Ultimate Carjunky
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May 20, 2012, 7:09 AM
Post #46 of 113
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Make sure your battery is disconnected when you go behind the panel. I believe you'll see a bunch of copper feed bars. Some of these fuses use the same feed bar on one side of the fuse. The other side of the fuse is connected to it's corresponding circuit it protects. I have a feeling you won't have a problem seeing what is wrong once you get the fuse panel opened up.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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r.foust
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May 20, 2012, 11:09 AM
Post #47 of 113
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ok jon i got thr fuse panel out and go lucky didnt half to disconnect the battery
so what am i looking for jon because i dont really see anything that looks out of place or anby currosion on anything from the back
thanks Ron
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Discretesignals
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May 20, 2012, 12:28 PM
Post #48 of 113
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If you look in the diagram, those fuses share power from the same feed with the ignition turned on. If you have power at the rest of those fuses and not at #9, there has to be a problem inside the fuse panel if the fuse checks good. Check really good where fuse #9 plugs in and the bars that come off it's connection inside the panel. Inspect the fuse really good too. Have had a couple that looked good, but were actually disconnected inside.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 20, 2012, 12:34 PM)
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r.foust
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May 20, 2012, 1:07 PM
Post #49 of 113
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ok jon i looked at all the connections and from what i can tell and see is that everything is in tack .
i also tugged on the wires going to the #9 fuse and they dont seem to be broken or anything at the back of the fuse panel at least
the wire coming from my ignition switch is orange/black rather then blue though
thanks Ron
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Discretesignals
Ultimate Carjunky
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May 20, 2012, 2:43 PM
Post #50 of 113
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Black/orange should be coming off the ignition switch for the blower motor fuse and a 30 amp breaker
Dark blue should be the feed wire for those fuses 9,10,11, and 12. Don't understand why your showing voltages at 10,11, &12 and not on #9. There has to be something wrong in there if you are indeed missing power at that fuse. Did you try checking voltages inside the fuse panel on the bus bars and the side of the #9 fuse that connects to the feed bar?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 20, 2012, 2:44 PM)
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