QuestionQUESTION: Hi Darren,
Fuse 23 gets power from the ignition switch (circuit A23) which in turn gets its power from fuse 8 in the PDC. Fuse 23 powers many relay actuation coils and the pcm. So check fuse 8. Fuses 24 and 25 get their power from the ASD relay (circuit A142) and that relay needs fuse 14 in the PDC as well as of course being activated by the pcm. So if the pcm isn't getting power then that might be the reason for no bus and no power to 24 and 25.
Please read the PS (below) and respond to it.
Thanks,
Roland
Fuse 8 was good, no fuses blown, not even those in 23,24, and 25 - it is just there is no power coming into the three fuse areas 23,24,25, the ASD relay was also good. I thought possibly the PCM went bad, but then wouldn't alot more items not have power, not just these three specific fuses? My thinking is that there has to be something that all three of these fuses that have something in common. As far as I can tell this car has coil packs on each of the cylinders, so my original thought of a bad coil doesn't make much sense to me. Is there suppose to be a main coil somewhere seperate from all these other coils? could that be bad and cause all three of these fuses to not get power?
ANSWER: Question:
What would cause a no bus error? The vehicle has 3 fuses in the distribution box, slot 23,24, and 25 with no power to them. The fuses were not blown - just no power to them. Car was running fine, turned it off and then it wouldn't start and gave the no bus error. The fuses are as follows: fuse 25 = 20 amp O2 SSR/ ALT/ EGR
fuse 24= 20 Amp Injector Coil
fuse 23= 20 Amp Relays
None of them have power coming into them. What would be a common denominator that would cause all 3 not to have power?
Question:
What would cause a no bus error? The vehicle has 3 fuses in the distribution box, slot 23,24, and 25 with no power to them. The fuses were not blown - just no power to them. Car was running fine, turned it off and then it wouldn't start and gave the no bus error. The fuses are as follows: fuse 25 = 20 amp O2 SSR/ ALT/ EGR
fuse 24= 20 Amp Injector Coil
fuse 23= 20 Amp Relays
None of them have power coming into them. What would be a common denominator that would cause all 3 not to have power?
Answer:
Hi Darren,
Fuse 23 gets power from the ignition switch (circuit A23) which in turn gets its power from fuse 8 in the PDC. Fuse 23 powers many relay actuation coils and the pcm. So check fuse 8. Fuses 24 and 25 get their power from the ASD relay (circuit A142) and that relay needs fuse 14 in the PDC as well as of course being activated by the pcm. So if the pcm isn't getting power then that might be the reason for no bus and no power to 24 and 25.
Hi Darren,
When you said originally the three fuses have no power, I assume that was when you had the key in "run" position, otherwise of course there would be no power to them.
Verify that you have 12v on fuse 8. If so then:
I would check the ignition switch for 12v on pin 7 which is coming in from fuse 8, and then turn the key to both the run position and the start position and check for 12v at pin 9 of the switch. That is the pathway from the battery to fuse 23 which you say shows no voltage. If it isn't fuse 8 being blown then it has to be the ignition switch or the wires connecting from fuse 8 to the fuse 23. Once you get 23 powered up, which powers the pcm, we'll have a better idea of what is further wrong.
Please rate my answers and consider a "yes" where you see the question about a nomination of me for "volunteer of the month.
Thanks,
Roland
---------- FOLLOW-UP ----------
QUESTION: Just a thought as I am not sure how everything is wired on this car from hell, but could it be a bad crankshaft postion sensor? Could this sensor cause the ecm to send no signal to ECM and thereby no signal to PCM which then shuts down power to those three fuse areas?
AnswerYes, that would shut off the ASD, but the ASD will only power fuses 24 and 25 when the engine is running, being cracked over, or for about 1 second when you first turn the key to run and to start. So don't expect to see 12v on 24 or 25 except under those conditions because the ASD relay will be "open" otherwise. Read my reply to your earlier question this morning. You have to get 12v on fuse 23 to begin to solve this problem.
