Strange electrical issues > computer sees low bat, load tests ok
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03-28-2010, 03:55 AM
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Strange electrical issues > computer sees low bat, load tests ok
I had actually started posting this over on another forum (the name seems to be censored out so may not be good. I will refrain from mentioning it further. 
) and did get some very good help (as best as could be had with how confusing this issue has been) but figured more eyes may be of good help. 
I'm mostly just going to copy/paste relevant pieces of info in here:
That's basically the gist of it. The most confusing part to me now is how without the engine running with all the big draw accessories running the volt gauge will nosedive but audibly/visibly the battery still has a good charge and the engine cranks right over (even with leaving said accessories on like the headlamps and front defrost). I do have a copy of the FSM for this thing and know how pretty much the whole charging system runs through the computer and the volt gauge on the dash is what the computer sees and not a direct connection to the battery (one reason I really wish I had a decent digital multimeter I could do real confirmed tests with). As already stated in the last quote I feel it is either the PCM is trying to go (although the engine runs just fine, it's just the electrical gremlin here) or a ground or power wiring to the computer is shot.
Anyone else have better ideas? Really appreciate any help.
) and did get some very good help (as best as could be had with how confusing this issue has been) but figured more eyes may be of good help. I'm mostly just going to copy/paste relevant pieces of info in here:
So this happened yesterday morning out of nowhere attempting to go to work. Attempt to start and when the key is cranked to start everything goes on the interior (I cannot remember if dash indicators and the odometer and such cut out during cranking under NORMAL conditions or not?) out and there's a loud and rapid clicking, no reaction at all from the motor. Upon further investigation it sounds like it is coming from the general vicinity of the PDU or the rear of the engine compartment on the driver side. Let off the key and everything interior-wise comes back. Dash guages and such come back so the PCM is operating properly. Voltage needle is just a hair above the line between 8 and 14. Even the fuel pump re-primes at this point (I cannot remember if the FSM mentioned anything about it doing so after a failed start, just that it ran for a couple seconds in the 'run' position to prime the system before starting the engine).
The defroster was on and the drivers door was open so I shut the defrost off and closed the door and killed all the electrical load I could (radio off too. Just the odometer and TRS indicator were lit and clock on the radio and whatever normal dummy lights on the dash) and finally it cranked right over like nothing was wrong. Not even any hesitation like the battery was sufficiently drained. Just going by the dash voltage gauge the alternator appears to be functioning normally with the voltage about a needle's width past 14V.
Took it to the shop to my trusted mechanic to have everything tested and he said everything looked ok. Load tested the battery, checked the alternator, all checks out.
Went out this morning and it kicked over just fine without issue after sitting for 12 hours.
...
My possible guesses are a) failing ASD relay? or b) starter solenoid?
This is an '00 SLT 4.7L with the electronic 45RFE btw.
The defroster was on and the drivers door was open so I shut the defrost off and closed the door and killed all the electrical load I could (radio off too. Just the odometer and TRS indicator were lit and clock on the radio and whatever normal dummy lights on the dash) and finally it cranked right over like nothing was wrong. Not even any hesitation like the battery was sufficiently drained. Just going by the dash voltage gauge the alternator appears to be functioning normally with the voltage about a needle's width past 14V.
Took it to the shop to my trusted mechanic to have everything tested and he said everything looked ok. Load tested the battery, checked the alternator, all checks out.
Went out this morning and it kicked over just fine without issue after sitting for 12 hours.
...
My possible guesses are a) failing ASD relay? or b) starter solenoid?
This is an '00 SLT 4.7L with the electronic 45RFE btw.
Well had another surprise this morning. Went out to run some errands and out of nowhere the voltage gauge pegs out. Thankfully we had already pulled into a parking lot so shut it off and went about our business. Came out 15 minutes later and started it and all is back to normal. Managed to get it to the mechanic again but because it was running fine there was nothing they could do. Though now the voltage gauge is a little higher than normal when running. I'd say half between 14 and the line after that when at speed, maybe less.
I have noticed though that since the other day, when the engine isn't running it runs a little low like two needles widths below the mark past 8 (I really need a multimeter for this stuff, can only go by the dash. God forbid the computer goes.). Though it doesn't seem to have troubles starting at this level, it seems to be just a slight bit slower crank by ear.
I have noticed though that since the other day, when the engine isn't running it runs a little low like two needles widths below the mark past 8 (I really need a multimeter for this stuff, can only go by the dash. God forbid the computer goes.). Though it doesn't seem to have troubles starting at this level, it seems to be just a slight bit slower crank by ear.
Even more confusion. Took it somewhere else to replace the battery and they actually gave the numbers off the load tester and said it gave 621 out of 650 CCA's.
Also did an impromptu test with the engine off but the key in the run position. HEadlights on, front defrost on with blower to max, radio on. Voltage gauge held for about 10 seconds before it did a rapid dive towards 8 and the check gauges light lit up. But immediately tried to start it and it cranked right over like nothing was wrong.
Also did an impromptu test with the engine off but the key in the run position. HEadlights on, front defrost on with blower to max, radio on. Voltage gauge held for about 10 seconds before it did a rapid dive towards 8 and the check gauges light lit up. But immediately tried to start it and it cranked right over like nothing was wrong.
We've run it around town though all day since this mess and no issues yet. Just a slightly higher than normal charging voltage (not anywhere near the 18 mark, but just past 14 but slightly higher than it has been) which could easily be explained if the computer is seeing something off-kilter compared to what is really there.
Well at least one constant is this issue of the gauge nosediving with the engine off if enough accessories are going but being able to start right up like the battery is fully charged. That I know for sure because we've done that test quite a number of times. I've even listened closely to the HVAC blower motor when it is full tilt and when the gauge drops I don't hear any audible difference which should be the case if it truly is draining the battery.
Only thing I can think of is something in the PCM is going or wiring between the battery and the PCM is messed somewhere (I did just look as best I could at all the easily accessible wiring and all looked good. There's some mild green oxidation on the main leads into the PDC but hardly a concern. Not like a huge white caked buildup.). Though as far as driveability and everything other than this charging system issue it is rock solid. Computer's not throwing any codes (only did once in the overcharging situation yesterday) and the engine's running fine.
Only thing I can think of is something in the PCM is going or wiring between the battery and the PCM is messed somewhere (I did just look as best I could at all the easily accessible wiring and all looked good. There's some mild green oxidation on the main leads into the PDC but hardly a concern. Not like a huge white caked buildup.). Though as far as driveability and everything other than this charging system issue it is rock solid. Computer's not throwing any codes (only did once in the overcharging situation yesterday) and the engine's running fine.
Anyone else have better ideas? Really appreciate any help.
Last edited by Vchat20; 03-28-2010 at 04:29 AM.
#2
03-28-2010, 10:14 AM
THE ULTI-MOD
you said you had the battery tested, did you have it replaced? it really sounds to me like it is just the battery going bad, i know that these trucks will act up if the battery is close to being completely shot, they can even test out OK and the truck still wants a new one, and if that battery is more than 4 years old you got your monies worth out of it anyway
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03-28-2010, 06:54 PM
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03-28-2010, 11:19 PM
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03-29-2010, 01:12 AM
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Sorry. Should have made the quotes a little more clear. Realized that after the fact.
The starting issue was a one time thing. Once I took it to the mechanic after finally getting started he tested everything including a load test of the battery and also cleaned the battery terminals real good (I double checked this myself. It's about as clean as I, personally, could possibly get it). Other than that one single time it has started up fine and no issues.
Couple days later the overcharging issue popped up and that was a single occurrence as well. After I noticed the gauge spike I shut it off, let it sit about 15 minutes, started back up. All is normal again.
Day after that we took it elsewhere for a second opinion on the battery. BEFORE he took it into the garage we did the accessory load test. Even with that he said the bat looked good with the reading of 621 of 650 CCA's. And as stated with all the accessories goin and headlamps on and the volt gauge pegged to the bottom it cranks right over still. This is the only real constant in this situation as it can be reproduced regardless of the conditions (this part has me the most confused unless the starters in these rigs are capable of cranking a big V8 at reduced voltage?). And in the same fashion, after it has been sitting a while the volt gauge reads a bit below the first mark but still starts up just as easily as it has been. If I shut it off and immediately turn it back on but don't start the volt gauge is half between that mark and 14.
I will try replacing the battery though next time I have the extra money around. It's the cheapest option anyways. Hope you understand how confused I am here. Because at face value it does not appear there is anything wrong with the battery. But really who knows. Sadly electrical gremlins plague this household. Between of an '89 Olds Cutlass Ciera, a '90 Mitsubishi Galant, a '96 Ford Windstar (The spawn of satan himself), and now this thing; All have had major electrical issues at some point.
The starting issue was a one time thing. Once I took it to the mechanic after finally getting started he tested everything including a load test of the battery and also cleaned the battery terminals real good (I double checked this myself. It's about as clean as I, personally, could possibly get it). Other than that one single time it has started up fine and no issues.
Couple days later the overcharging issue popped up and that was a single occurrence as well. After I noticed the gauge spike I shut it off, let it sit about 15 minutes, started back up. All is normal again.
Day after that we took it elsewhere for a second opinion on the battery. BEFORE he took it into the garage we did the accessory load test. Even with that he said the bat looked good with the reading of 621 of 650 CCA's. And as stated with all the accessories goin and headlamps on and the volt gauge pegged to the bottom it cranks right over still. This is the only real constant in this situation as it can be reproduced regardless of the conditions (this part has me the most confused unless the starters in these rigs are capable of cranking a big V8 at reduced voltage?). And in the same fashion, after it has been sitting a while the volt gauge reads a bit below the first mark but still starts up just as easily as it has been. If I shut it off and immediately turn it back on but don't start the volt gauge is half between that mark and 14.
I will try replacing the battery though next time I have the extra money around. It's the cheapest option anyways. Hope you understand how confused I am here. Because at face value it does not appear there is anything wrong with the battery. But really who knows. Sadly electrical gremlins plague this household. Between of an '89 Olds Cutlass Ciera, a '90 Mitsubishi Galant, a '96 Ford Windstar (The spawn of satan himself), and now this thing; All have had major electrical issues at some point.
Last edited by Vchat20; 03-29-2010 at 01:23 AM.
#7
03-30-2010, 08:24 AM
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Had a galant before the D. It had a bad alternator and I got it replaced w/ the wife's permission! 
Here's the story: I picked up my buddy to go car shopping and noticed that the battery gauge would flucuate between low and high. Figured out that the faster I went, the better the alternator worked. So during the day, I would speed all over the place to keep the battery charged. But that night, wifey and I went to her sister's and she started the galant and the car died. LOL! No charge! So I blamed her for it and she just said to replace whatever needed replacing! LOL! She still to this day think she killed a car! LOL! Okay, back on topic. V, did you check the alternator?
Here's the story: I picked up my buddy to go car shopping and noticed that the battery gauge would flucuate between low and high. Figured out that the faster I went, the better the alternator worked. So during the day, I would speed all over the place to keep the battery charged. But that night, wifey and I went to her sister's and she started the galant and the car died. LOL! No charge! So I blamed her for it and she just said to replace whatever needed replacing! LOL! She still to this day think she killed a car! LOL! Okay, back on topic. V, did you check the alternator?
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#8
03-30-2010, 01:40 PM
THE ULTI-MOD
Had a galant before the D. It had a bad alternator and I got it replaced w/ the wife's permission! Here's the story: I picked up my buddy to go car shopping and noticed that the battery gauge would flucuate between low and high. Figured out that the faster I went, the better the alternator worked. So during the day, I would speed all over the place to keep the battery charged. But that night, wifey and I went to her sister's and she started the galant and the car died. LOL! No charge! So I blamed her for it and she just said to replace whatever needed replacing! LOL! She still to this day think she killed a car! LOL! Okay, back on topic. V, did you check the alternator?
Here's the story: I picked up my buddy to go car shopping and noticed that the battery gauge would flucuate between low and high. Figured out that the faster I went, the better the alternator worked. So during the day, I would speed all over the place to keep the battery charged. But that night, wifey and I went to her sister's and she started the galant and the car died. LOL! No charge! So I blamed her for it and she just said to replace whatever needed replacing! LOL! She still to this day think she killed a car! LOL! Okay, back on topic. V, did you check the alternator?, now dont let her read this thread