Will it never end?
#41
+1. As Jeremy Clarkson would say, brilliant.
Fuse blocks might help reduce the number of steps. Postulating 8 fuse blocks of 16 fuses each, physical operations:
4 fuse blocks disconnected, then 2 fuse blocks disconnected, then 1 fuse block disconnected, then 8 fuses, then 4 fuses, then 2 fuses, then 1.
Physical operations = 4+2+1+8+4+2+1 = 22
Time = 7 days.
Q.E.D. <== (always wanted to use that, and fully expected to be proven wrong now that I have)
Fuse blocks might help reduce the number of steps. Postulating 8 fuse blocks of 16 fuses each, physical operations:
4 fuse blocks disconnected, then 2 fuse blocks disconnected, then 1 fuse block disconnected, then 8 fuses, then 4 fuses, then 2 fuses, then 1.
Physical operations = 4+2+1+8+4+2+1 = 22
Time = 7 days.
Q.E.D. <== (always wanted to use that, and fully expected to be proven wrong now that I have)
[edit: had not seen post #40 when posting the above. I pretty much agree with that post. But why would we need to institute a new 30-minute test period as we pull each fuse under "random" search? Seems to me, if we're already in sleep mode, we're just looking for the fuse that makes the current drop.]
Last edited by Dennis07; 11-19-2011 at 04:48 PM.
#42
Rev. Sam, just a thought. When I first bought my '98 XK8 the previous owner said I had to run the car at least every 3 days or the battery would go dead. While I went about repairing the little quirks our cars have I noticed the trunk lights wouldn't work. Both bulbs burner out. Replaced with new bulbs, still didn't work. The lights were staying on all the time because of a bad switch. According to this forum this is another weak spot you have to watch. Replaced switch. Had car sit for over 3 weeks while on vacation. When I came home I had no problem starting. With all the work you were doing in the trunk, while working on you fuel pump, you might have done something to switch. Jack
#43
Pinpoint in 5,6,or 7 rounds
If the approach of pulling each of the 5 fuse box cables is used, that is already 5 rounds. If the fuse box containing the defective circuit is one of the smaller fuse boxes, containing say 8 fuses, and a linear search is applied, then by the law of averages, 4 further checks will be required. That is 9 operations on average, with a minimum of 6 and a maximum of 17.
The binary search on 128 fuses is guaranteed to locate the circuit, *if* it is a fused circuit, in exactly 7 operations.
The binary search on 128 fuses is guaranteed to locate the circuit, *if* it is a fused circuit, in exactly 7 operations.
Although I did pull the cables and brute force the PASS SIDE FB, If I would have to pinpoint a single fuse circuit drain on my 2002 again, here is my thinking:
- ENGINE COMPARTMENT FUSE BLOCK (ECFB) takes 2 rounds to pinpoint and 3 additional rounds to pinpoint the culprit fuse circuit for a total of 5 rounds.
- ENGINE MANAGEMENT FUSE BLOCK (EMFB) takes 2 rounds to pinpoint and 4 additional rounds to pinpoint the culprit fuse circuit for a total of 6 rounds.
- Either DRIVER SIDE FUSE BLOCK (DSFB) or LUGGAGE COMPARTMENT FUSE BLOCK (LCFB) takes 3 rounds to pinpoint and 4 additional rounds to pinpoint the culprit fuse circuit for a total of 7 rounds.
- PASSENGER SIDE FUSE BLOCK (PSFB) takes 2 rounds to pinpoint and 4 additional rounds to pinpoint the culprit fuse circuit for a total of 6 rounds.
(Let's assume that the culprit is in ECFB but we do not know it.)
Disconnect the cables to ECFB and EMFB and do Round 1 (~30 minutes)
Ah ha! We have an indication that it is indeed one of these two, so we connect one cable back to either ECFB or EMFB and run Round 2.
Ah ha! We have an indication that it is indeed in the ECFB.
We are now ready to start pulling fuses for Round 3, but which ones?
Six fuses, #9,12,14,16,18,22, are the active ones that we are concerned about. The other fuses are inactive because they are controlled by the ignition key which has turned off that fuse block relay that provides current to them. (Ok, the relay contacts could be stuck causing a multiple fuse circuit problem that is beyond the scope of this single fuse circuit search)
So, since there are in effect 6 fuses, lets use the "divide and conquer method" and pull out half of the fuses, which is 3, and then run Round 3. (Always make sure the fuse block cable is connected when going through these fuse pulling routines)
Next push in or pull out (as required) half of 3 which is 2 as we will always round up to the next whole number and then do Round 4.
Lastly, push in or pull out half of 2 which is 1 and run Round 5.
Ah ha! We have an indication that it is indeed that one fuse circuit!
(Now, let's assume that the previous Round 1 and Round 2 indicated that the culprit is in EMFB but we do not know which fuse.)
The EMFB has 11 active fuse circuits. (Fuse # 1,2,3,4,5,8,9,11,15,17,18)
Again, use divide and conquer. Half of 11 is 6, so we pull 6 fuses for Round 3.
For Round 4, push in or pull out 3 fuses
For Round 5, push in or pull out 2 fuses
For Round 6, push in or pull out 1 fuse
Ah ha! We have an indication that it is indeed that one fuse circuit!
(Now, let’s assume that the previous Round 1 Indicated that neither the ECFB or EMFB had the culprit. So, having spent Round 1,we can go on to Round 2and Round 3 in similar fashion for the next pair, DSFB and LCFB, disconnecting both of their cables for Round 2 and reconnecting one cable for Round 3.
DSFB has 12 active fuses ,#1,2,3,5,6,7,8,11,13,15,17,and 18.
Pull 6 for Round 4
Push or pull 3 for Round 5
Push or pull 2 for Round 6
Push or pull 1 for Round 7
Ah ha! We have an indication that it is indeed that one fuse circuit!
Or if instead it is the LCFB, then:
LCFB has 10 active fuses ,#1,2,9,10,12,14,16,18,20,and 22.
Pull 5 for Round 4
Push or pull 3 for Round 5
Push or pull 2 for Round 6
Push or pull 1 for Round 7
Ah ha! We have an indication that it is indeed that one fuse circuit!
Finally, let’s assume that previous Round 1 of the ECFB and EMFB pair and Round 2 of the DSFB and LCFB pair indicate that none of those 4 fuse blocks has the culprit. Then by default, we know that the culprit is in the PSFB. This is the block that I would have difficulty disconnecting the cable. But,since we know the culprit is in this block, we can go ahead to this fuse pulling routine Round 3 with it connected:
PSFB has 12 active fuses ,#1,2,4,5,6,7,8, 9,11,15,17,and 18.
Pull 6 for Round 3
Push or pull 3 for Round 4
Push or pull 2 for Round 5
Push or pull 1 for Round 6
Ah ha! (note:some of my ancestors were pirates)We have an indication that it is indeed that one fuse circuit!
And so, that’s my thinking.
Last edited by Dr. D; 11-19-2011 at 11:36 PM. Reason: Excess Spacing
#45
Rev. Sam, just a thought. When I first bought my '98 XK8 the previous owner said I had to run the car at least every 3 days or the battery would go dead. While I went about repairing the little quirks our cars have I noticed the trunk lights wouldn't work. Both bulbs burner out. Replaced with new bulbs, still didn't work. The lights were staying on all the time because of a bad switch. According to this forum this is another weak spot you have to watch. Replaced switch. Had car sit for over 3 weeks while on vacation. When I came home I had no problem starting. With all the work you were doing in the trunk, while working on you fuel pump, you might have done something to switch. Jack
Hey Pophen, Where is the switch? I have a similar issue and have not been able to find it, my trunk lights do not come on so I just assumed it was not them, but this may be my ticket.
#46
UPDATE: Oops...Gus had posted about this earlier ....sorry Gus
adam699 on the XJ forum just made reference to this 'fusebox ammeter' for 15 bucks at Harbor Freight: 20 Amp Automotive Fuse Circuit Tester. Cool little device. Might be helpful here...
adam699 on the XJ forum just made reference to this 'fusebox ammeter' for 15 bucks at Harbor Freight: 20 Amp Automotive Fuse Circuit Tester. Cool little device. Might be helpful here...
Last edited by WhiteXKR; 11-23-2011 at 07:54 AM.
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mcbeefsteak (11-23-2011)
#47
500 ma is 10 times the standard as I'm sure you know. I have had luck installing my ammeter between the battery terminal and the positive battery cable, then pulling fuses until it drops. I suggest starting with the trunk light circuit. I think this uses a microswitch in the latch and these seem more vulnerable to failure than other types of switches. The same goes for all openings, doors, glove box and so on. Things that don't work with the ignition off can be ignored. I too think that a follow up on the Autozone test is worthwhile. I bought a 1000 amp battery load tester from Harbor Freight that works fine and I trust it. Nice to be able to do this test whenever you want. The battery should measure 14.4 v across the terminals with the engine running, or the alternator may be duff.
#48
#49
#52
I think I have a combination of weak battery and a drain coming from the circuit that powers the lights inside the car. If I pull the fuse to the lights (driver's side fuse box, second fuse up on the right) the current draw drops to about 200 miliamps, which is about a 60% reduction over the 500 miliamps I see with the fuse installed. Even then, however, the following morning the car is slow to crank and I then have to reprogram my windows. I bet a new battery will make the current drain unnoticeable unless I leave the car parked for a week or more. But the people at the auto parts store where the battery is under warranty say that the battery is fine, so they don't want to replace it under warranty. I might just bite the bullet and spend $200 on a new battery. Before I do that, though, I'm going to completely disconnect the battery this afternoon after it gets a full charge and then see how the car cranks tomorrow morning.
#55
If it is not the bluetooth, another strategy is to unplug control modules one at a time.
In some Mercedes, it is very common for the CAN bus trancievers in (usually) the seat modules to partially fail and lose their ability to go to sleep....there could be something along those lines going on here.
In some Mercedes, it is very common for the CAN bus trancievers in (usually) the seat modules to partially fail and lose their ability to go to sleep....there could be something along those lines going on here.
#56
#57
I think I have a combination of weak battery and a drain coming from the circuit that powers the lights inside the car. If I pull the fuse to the lights (driver's side fuse box, second fuse up on the right) the current draw drops to about 200 miliamps, which is about a 60% reduction over the 500 miliamps I see with the fuse installed. Even then, however, the following morning the car is slow to crank and I then have to reprogram my windows. I bet a new battery will make the current drain unnoticeable unless I leave the car parked for a week or more. But the people at the auto parts store where the battery is under warranty say that the battery is fine, so they don't want to replace it under warranty. I might just bite the bullet and spend $200 on a new battery. Before I do that, though, I'm going to completely disconnect the battery this afternoon after it gets a full charge and then see how the car cranks tomorrow morning.
#58
Here some info on a 2000MY car:
5 Turn the ignition ON (position II); wait five seconds; turn the ignition fully OFF. Close and lock all doors.
6 Wait thirty seconds. Check that all interior lamps have 'timed out'. Record the current reading on the DVM. (Select a more sensitive range where appropriate). This reading should normally be 250 - 500 milliamps.
7 Wait for a further sixty minutes; again record the DVM reading. This reading should not exceed 40 milliamps. Where a final reading in excess of 40 milliamps is recorded, this is an indication of a spurious current drain from the battery; this must be traced and rectified.
This info comes from tsb 414-06, that discusses a faulty O2 sensor relay that could cause a drain.
5 Turn the ignition ON (position II); wait five seconds; turn the ignition fully OFF. Close and lock all doors.
6 Wait thirty seconds. Check that all interior lamps have 'timed out'. Record the current reading on the DVM. (Select a more sensitive range where appropriate). This reading should normally be 250 - 500 milliamps.
7 Wait for a further sixty minutes; again record the DVM reading. This reading should not exceed 40 milliamps. Where a final reading in excess of 40 milliamps is recorded, this is an indication of a spurious current drain from the battery; this must be traced and rectified.
This info comes from tsb 414-06, that discusses a faulty O2 sensor relay that could cause a drain.
#59