Cranks, but no spark, codes C1155, U1262 and P0340

Tiny
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  • MEMBER
  • 2002 MERCURY COUGAR
  • 2.5L
  • V6
  • 2WD
  • MANUAL
  • 157,890 MILES
Initially I had nothing. Turn the key only dash lights radio. So I checked the power distribution box under the hood and found a relay fuse had been broken plus a 40A fuse blown, so I change them, tried it. The 40A blew on the spot. So instead of replacing it again I decided to place a jumper wire on the blown fuse. I also need to say that plugged in my code reader and had three pop up. They were C1155 LF speed sensor malfunction, U1262 standard communication protocol communication bus malfunction, P0340 module camshaft position sensor A circuit (bank 1 or single sensor) confirmed. Now I found the camshaft sensor unplugged so I connected it, the speed sensor was damaged so I replaced it. I then went ahead and pulled the PCM to visually look at it and see if I could notice anything, hot spots, corrosion, etc, then reconnected it. I did finally get it started and running.
It sounded good except for an intermittent grinding sound coming from near the top motor mount on the passenger side. But anyway I clear the U1262 and P0340 codes and it still started and ran, but when I finally change the speed sensor C1155 and cleared that code and then decided to start it to let the PCM cycle again to check everything one more time it is at this time I could not get the car to start again. The fuel pump does work, the relays have been checked. I have checked the coil pack (one six pack) it itself seems to be okay, but no power getting to it. I have already changed out the crankshaft sensor during this time, still no luck. At this time the engine cranks just fine but no spark. My worst case scenario is that using that jumper wire might have overheated a circuit in the PCM. But until I can get it running again I know the PCM will not give anymore codes or at least it has not yet through just cranking it, I have checked already. What have I overlooked? There are other possible causes I have learned about, I want to try this way before proceeding on first.
Monday, April 9th, 2018 AT 11:06 PM

12 Replies

Tiny
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First of all, never jump across a fuse empty socket, you could ruin other things. The reason the fuse was blowing cause the amperage was too high and most likely will burn something up without a fuse in there. If anything, install a auto resetting circuit breaker of the same amperage if you want to be able to power something up in order to test or first find out why the fuse keeps blowing or have plenty of ten cent fuses handy.
Now, let's move onto the no power to the coils, are you sure the key was on run?
The ignition coils are fed from the PCM power relay and fuse 41, both in the battery junction box and the ignition switch.
Now about that 40a fuse, you never mentioned which fuse it was, was it #42?
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Tuesday, April 10th, 2018 AT 8:10 AM
Tiny
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Okay, first I did not put the jumper wire in an empty slot I know better than that, I put it in the fuse itself and then put the fuse back in its slot. Second it is a 20A fuse, that is my fault sorry I double checked that because I had 40A in my mind. And it is #40, but I get the point thank you. As far as the ignition coil pack, it is also a 20A fuse in #41 but it appears to be okay. I did pull it and checked the circuit with my test light and it had power. Yes I had the key on, the dash lights came on as well as the radio. I will go out and check again to make sure I did not miss anything.
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Tuesday, April 10th, 2018 AT 11:40 AM
Tiny
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I still do not understand though about this jumper wire. If you are jumping across the fuse whether or not the fuse is in, the possibility still remains that you could burn something up.
Remove that PCM power relay, check the prongs in the empty socket and make sure one is hot all the time and then an additional is hot when the key is on run/start, that comes from the ignition switch.
It just so happens the ignition switch is fed from that #40 fuse in the BJB, so it appears that may be the problem since that fuse keeps blowing. That fuse #40 feeds several things, including the ignition switch, light switch and a fuse #26 in the central junction box, so I would first remove that fuse #26 and see if that fuse #40 stops blowing, if not, disconnect the harness plug at the light switch and check again, lastly the harness to the ignition switch to figure out where the short circuit is first of all.
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Tuesday, April 10th, 2018 AT 12:27 PM
Tiny
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Okay sound good thank you for that. Also, I have to apologize again about those 20A
fuses. I know the jumper wire should not be used at all in todays vehicles especially.
The jumper wire is in #41 fuse not #40. I still do some things old school or pre- computer. But I will go try this new information an see what happens. Thanks
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Tuesday, April 10th, 2018 AT 2:07 PM
Tiny
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Okay, I did pull the PCM power relay R2 and tested the prongs in the empty socket, but #3 came up hot with out the key and #1 only went hot with the key on. Pretty much the exact opposite especially when the diagram on the side of the relay shows #3 as the switch side.
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Tuesday, April 10th, 2018 AT 2:32 PM
Tiny
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Sometimes the relay can be put in upside down.
Anyhow, try replacing that pcm relay with a new relay just incase it is shorted out and causing that fuse #41 to blow and try everything again.
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Tuesday, April 10th, 2018 AT 3:34 PM
Tiny
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Okay, I can change it out, even though it is a new relay. But it is a five point relay on this
car, so it goes in the slot only one way.
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Tuesday, April 10th, 2018 AT 4:25 PM
Tiny
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Okay, never mind then, if it is new.
Okay, the fuses' tested okay, and you had voltage in the empty relay socket, so now put your finger tips on that relay and feel if it clicks or not when the key is turned to both start and run.
If not, then you may have a faulty ground from that relay, but if it does click and no voltage still to the coils, check if voltage is making it to the coils and if not, check along that green/blue wire to find the short/open.
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Tuesday, April 10th, 2018 AT 5:02 PM
Tiny
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Okay thanks I will check into that. I was messing with it earlier and also noticed the the junction box was not secure in its position, so I thought I would check under that to see
what the wires look like.
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Tuesday, April 10th, 2018 AT 6:21 PM
Tiny
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It could be.
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Tuesday, April 10th, 2018 AT 6:47 PM
Tiny
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Sorry I took so long but I did find a harness connector had partially separated so I got it snapped back together and have power once again back at the coil pack. Thanks you.
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Monday, April 30th, 2018 AT 2:37 PM
Tiny
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You are welcome!
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Monday, April 30th, 2018 AT 2:49 PM

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