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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Haven't driven the IROC in a few days, might even have been a week. Went to pull it out today and the battery was dead. What's the easiest way to identify what circuit is killing my battery?
Haven't driven the IROC in a few days, might even have been a week. Went to pull it out today and the battery was dead. What's the easiest way to identify what circuit is killing my battery?
First (it has to be said) Are you 101% certain the battery hasn't failed ? If your "bet your life sure" the battery is OK ;
Start with a fully charged battery .
Put a home made test light (made out of a #1156 taillight bulb in a pigtail socket with two wires) between one of the battery's wires and it's battery post
(with the other battery wire hooked up normally , of course) .
The bulb should be rather bright . Now , one after another , unplug the fuses till you find which fuse makes the light go out (or get noticeably dimmer) , that fuse is powering your excessively drawing circuit . If no fuse pulled makes the light go dim try disconnecting the alternator , a shorted diode can very easily drain a battery in a few days (as well can bad capacitors in any aftermarket stereos , amps , etc)
First (it has to be said) Are you 101% certain the battery hasn't failed ? If your "bet your life sure" the battery is OK ;
Start with a fully charged battery .
Put a home made test light (made out of a #1156 taillight bulb in a pigtail socket with two wires) between one of the battery's wires and it's battery post
(with the other battery wire hooked up normally , of course) .
The bulb should be rather bright . Now , one after another , unplug the fuses till you find which fuse makes the light go out (or get noticeably dimmer) , that fuse is powering your excessively drawing circuit . If no fuse pulled makes the light go dim try disconnecting the alternator , a shorted diode can very easily drain a battery in a few days (as well can bad capacitors in any aftermarket stereos , amps , etc)
Happy hunting ...
The only things i bet my life on is god... and my Kimber 1911 but the battery is new (stamped 03/19). I'll test the battery and assemble the test light.
The batteries in my F350 superduty go dead after sitting for a few weeks. I know exactly what kills them. The alarm system. Batteries are new but the alarm system is a constant trickle drain and will kill the batteries in a few weeks. If I need to let the truck sit for an extended period of time, I hook a smart charger onto the batteries and leave it plugged in. That way the batteries stay charged and when fully charged, the charger stops charging. If I forget to plug it in, it's even better than a security system. Can't start the truck, can't steal it.
Had to bring this thread back. 1st day of 50+ weather I brought her out, a couple days later boom battery dead as ish. Where do you get a 2 wire #1156 taillight bulb in a pigtail socket? I searched autozone.com, they have the bulb of course but I couldn't find the socket. Is it easier to hit the JY and grab one off a car of some kind?
It was also mentioned "bad capacitors in any aftermarket stereos , amps , etc" could also drain it in a flash and ever since I got the car the aftermarket head-unit acts WOOZY. Like push a button and the display cuts out, buttons become non responsive, etc...
Had to bring this thread back. 1st day of 50+ weather I brought her out, a couple days later boom battery dead as ish. Where do you get a 2 wire #1156 taillight bulb in a pigtail socket? I searched autozone.com, they have the bulb of course but I couldn't find the socket. Is it easier to hit the JY and grab one off a car of some kind?
It was also mentioned "bad capacitors in any aftermarket stereos , amps , etc" could also drain it in a flash and ever since I got the car the aftermarket head-unit acts WOOZY. Like push a button and the display cuts out, buttons become non responsive, etc...
In lieu of searching in vain for a two-lead 1156 socket, just buy a test light:
Often times, you can take the test light and just probe the back of the fuses without having to pull them to find the drain. Just make sure the fuse you're probing is supposed to be dead with the key off or you'll get a false positive (no pun intended).
Last edited by paulo57509; Mar 6, 2020 at 02:42 PM.
Reason: Grammar
I'm going to go out on a limb and say what you're about to see has to have something to do w/ my issues... both the battery drain and the woozy radio operation.
Hi Ed , sorry I missed your earlier post last month asking about the test light , and I'd like to share my thoughts as to what you see there .
You say the two symptoms are the battery being mysteriously drained and the radio behaving oddly . That 10 amp radio fuse is only supposed to have power on it with the key in either the ACC or run positions , in other words with the key off there should be no power to that fuse for it to be able to be passing the power that's draining the battery . But , seeing the fusebox melted there and knowing the battery IS in fact being drained , my guess is that the radio is wired improperly and the improper wiring is "Backfeeding" through that fuse when the key is off and powering something else that's on the same ignition switch contact as the radio .
A great test would be to probe each of those contacts where the fuse goes with a test light (with the key off) to see if it's got 12 Volts on either of the contacts . If there is 12 Volts there with the key off my bet is that the radio's "memory" circuit (Orange wire , always hot) has been inadvertently connected to the radio's "Power" circuit (Yellow wire , only hot with the key on or ACC position) .....
PS , I forgot to ask , with the radio miswired as I think it could be , that would make the radio operable all the time , even with the key off . Tell me , does the radio work without the key ?
Last edited by OrangeBird; Apr 4, 2020 at 11:00 AM.
Hi Ed , sorry I missed your earlier post last month asking about the test light , and I'd like to share my thoughts as to what you see there .
You say the two symptoms are the battery being mysteriously drained and the radio behaving oddly . That 10 amp radio fuse is only supposed to have power on it with the key in either the ACC or run positions , in other words with the key off there should be no power to that fuse for it to be able to be passing the power that's draining the battery . But , seeing the fusebox melted there and knowing the battery IS in fact being drained , my guess is that the radio is wired improperly and the improper wiring is "Backfeeding" through that fuse when the key is off and powering something else that's on the same ignition switch contact as the radio .
A great test would be to probe each of those contacts where the fuse goes with a test light (with the key off) to see if it's got 12 Volts on either of the contacts . If there is 12 Volts there with the key off my bet is that the radio's "memory" circuit (Orange wire , always hot) has been inadvertently connected to the radio's "Power" circuit (Yellow wire , only hot with the key on or ACC position) .....
PS , I forgot to ask , with the radio miswired as I think it could be , that would make the radio operable all the time , even with the key off . Tell me , does the radio work without the key ?
No the radio doesn't function without the key, pulled the radio and nothing "looks" miswired. I did clean the fuse area / reinstalled fuse, installed the freshly charged battery, grabbed my HF Test Light and probed both the front contacts and what I believe to be the yellow wire in the rear of the fuse box and no light.
Ok I think you are not performing the draw test correctly here. Disconnect the negative side of the battery, and put the test light (must be an incandescent test light) in series with the negative battery terminal and the battery post. With all the doors shut the light should be out. Open the door and the dome light should make the test light illuminate. Pull the fuse for the dome light and then once again the light should be out.
If the light is not out with all the doors shut, then you need to pull fuses till it is. Remember to shut the door and/or pull the dome fuse while testing.
From reading the thread I don't see that you have done the test properly yet.
You really need a multimeter. You can start unplugging fuses with the meter hooked to the battery and it will tell the story. It’s not complicated just follow directions. Get on google or YouTube and search “parasitic draw test”
You can also use the meter to verify that your alternator is charging correctly.
The only things i bet my life on is god... and my Kimber 1911 but the battery is new (stamped 03/19). I'll test the battery and assemble the test light.
Thanks!
I'll see you a Kimber and raise you two Series 70's
You really need a multimeter. You can start unplugging fuses with the meter hooked to the battery and it will tell the story. It’s not complicated just follow directions. Get on google or YouTube and search “parasitic draw test”
You can also use the meter to verify that your alternator is charging correctly.
150 milliamps would drain a marginal battery. Also the alternator can be an intermittent drain. I had a cold solder joint in a regulator that caused an intermittent drain.
The parasitic drain on my 86 Trans Am is less than 20 milliamps. That's with a modern stereo and all the factory options.
Went out this morning, redid the test w/ the radio fuse removed and got the same .145A draw. Moving on to testing the alternator to make sure it's charging the battery. Amps / Volts at battery terminals while running? The differences in the two videos below confused me...
145 milliamps may in fact BE your problem. It should be a lot lower. Here's my truck, which is running an aftermarket stereo and the dash clock. It's an 84 Jimmy:
My 86 TPI Trans Am was in the neighborhood of 20 IIRC. I recently tested it due to the aforementioned cold solder joint VR issue.
Here's with the door ajar:
So you are running about 1/4 of a normal incandescent dome light. Coupled with a marginal (cheap, insufficient charge, damaged from cold w/low charge, etc) battery and a few days sitting - yeah that's going to kill it off.
I really appreciate that GD, went out and redid test with all fuses removed... draw never dipped below .133A. How do I test my alternator w/ the meter? You bringing up the alt made sense if you drive the car, battery isn't being recharged the way it should, or is drawing as car sits, boom battery dead. I'd like a physical test before swapping parts.
Last edited by 92RS-HeritageEd; Apr 5, 2020 at 02:40 PM.
Just put the meter (set to DC volts with ideally about a 20v scale) across the battery while running. Should be 13.5 - 14.5v at idle. Ideally should be on the higher end of that and if not I like to see it increase with some RPM.
Unplug the alt to check if the mA draw goes down with it disconnected.
Well if you have pulled out ALL the fuses, and disconnected the ALT..... what is wired on your car with no fusing? Because whatever that is.... it needs a fuse!
Did you pull the fuse in the holder near the battery? That's the one for the TPI.
Thanks GD for the reminder on that forgotten fuse and everyone who chimed in on helping me.... time to break out the service manual... and see what's all on that circuit
So here we have it, it looks like i'll need to repeat the test unplugging the FP/OPS, FP Replay, and ECM one at a time. That's if I'm reading this correctly.
Last edited by 92RS-HeritageEd; Apr 5, 2020 at 06:33 PM.
Hi Ed , first off , my apologies for earlier saying the amount of draw you have is ok when in fact it isn't , I oopsed a decimal point there and although my eyes saw (and typed) .15 (150 MA.) my brain was thinking .015 (15 MA.)
Anyway , yes , try unplugging the oil pressure switch , the fuel pump relay , and then the ECM to see which of them makes the 150 MA. drain stop .
PS , as to the melted radio fuse , since you said the radio didn't work with the key off it isn't miswired in the way I suspected . I'm now left to wonder if the melted fuseholder is either the result of a simple loose connection between the fuse and it's holder causing the heat , or if perhaps the aftermarket radio (possibly being more powerful in output watts to the speakers) is drawing a bit more on it's input side than the stock radio did and heated up the fuse ?
Np @OrangeBird no normally operating radio would've caused that damage so I'll be replacing the radio too. Right after my last post I took a chance... put the fuse back in and disconnected the FP relay, redid test and draw remained at the low .017 reading. Tomorrow I'll slap in this new FP relay I had on the shelf. If that doesn't resolve I'll keep working all the way back to the pump.
So went out on lunch, slapped in the new FP Relay, tested and boom draw remained at the low .017 A reading. Now to hook the battery back up, start & tun it for a bit and turn it off. Then i'll wait till Friday to try starting it to see if the matter is resolved.
Interesting. Partially shorted NO contacts. Did you put in a high volume pump that draws more current than normal? Could be that the contacts are burned and partially welded. Autopsy is warranted as well as pump current draw and evaluation of existing circuit suitability.
Interesting. Partially shorted NO contacts. Did you put in a high volume pump that draws more current than normal? Could be that the contacts are burned and partially welded. Autopsy is warranted as well as pump current draw and evaluation of existing circuit suitability.
GD
Did you put in a high volume pump that draws more current than normal? Nope Could be that the contacts are burned and partially welded? Nope, Def the radio fuse
"Autopsy is warranted as well as pump current draw and evaluation of existing circuit suitability".... Absolutely agreed
No signs of even a scorch on the FP Relay connector or old relay. With all fuses in and new relay in place it shot right back up to .145A after reconnecting the battery and disconnecting it to double check the source was found. Back to FP Fuse removed = .017A draw or .145 w/ new Fuse & new FP relay...
Last edited by 92RS-HeritageEd; Apr 6, 2020 at 04:56 PM.
Update: Given the issues above I pulled the FP Fuse, the OPS connector, hit both of those w/ CRC QD Electronics Cleaner & small brush before reconnecting. Plugged back in the old FP relay and boom 019A draw. The pic is after connecting / disconnecting the battery the to retest amp draw. Hope it holds...
I suspect you have a partial ground somewhere in the harness that runs the fuel pump relay. Causing the FP relay coil to draw current (though not enough to close the contacts and run the pump). I also suspect that since you disconnected, moved, cleaned etc all the connectors involved that you will find this harness damage near the connectors or inside them. I suppose that "dirt" inside the connectors, if it were sufficiently conductive, might cause the problem also - though this seems a bit far fetched and I can't say that I've seen that happen in recent memory.
For the record - I was talking about the contacts on the *inside* of the FP relay (not the wiring harness connector contacts). But apparently that's not the issue given the new information.
GD
Last edited by GeneralDisorder; Apr 6, 2020 at 06:06 PM.
I suspect you have a partial ground somewhere in the harness that runs the fuel pump relay. Causing the FP relay coil to draw current (though not enough to close the contacts and run the pump). I also suspect that since you disconnected, moved, cleaned etc all the connectors involved that you will find this harness damage near the connectors or inside them. I suppose that "dirt" inside the connectors, if it were sufficiently conductive, might cause the problem also - though this seems a bit far fetched and I can't say that I've seen that happen in recent memory.
For the record - I was talking about the contacts on the *inside* of the FP relay (not the wiring harness connector contacts). But apparently that's not the issue given the new information.
GD
Don't know if it adds value... the ops connector was replaced at some point prior to my ownership. I'll check for 12+ V and try starting it Friday by then the battery would normally be dead so we'll see.
As for the RADIO fuse, a standard 10A installed there might not support the load of an aftermarket head/amplifier. Even the most efficient units using MOSFET outputs are only about 60-80% efficient at peaks. Thus, if the system is delivering anything near 100W a 10A fuses might not survive, but it would likely get and remain pretty warm. All that heat needs to go somewhere.
Parked her to pull out my 300 for it's fall prep, and itshappened again! However this go round the car tries to start but doesn't. Best way i can describe it is from the key turn it sounds like it's going to fire but she just dies as she turns over. If you give it gas, it *tries* to run. In fear of damage, i didn't force it to run long. No SES light, not running long enough to log.
*The original fix was fixing a broken wire on the OPS, and I thought it was that or the battery this go round since it wouldn't charge, nor would the car jump.
**Found one of three wires on the OPS, had a bare spot touching the firewall as well as the above noted wire repair failing. Covered the bare spot, repaired the repair, same dang outcome.
Could I have damaged my ECM?
Can the OPS be tested w/ a MM? The harness connector?
So today I repaired the Orange wire to the Oil Pressure Sensor, checked the repairs, did the amp draw test (0.02A), checked every fuse and used my spare ECM w/ the same outcome.
Battery is new off the shelf, charged to 12.8v and I get 44psi fuel pressure. I happened to observe 2 plug wires where the insulation was scorched. I think they touched the manifold, I've zip tied them out of the way for now. Idk how i'm going to test for spark, it doesn't crank long enough. The car has always started on the 1st engine revolution however now it's like it dies upon ignition/combustion?
Drove this just yesterday, was doing some other troubleshooting this morning, put her back together and went in for coffee. Came back out and went to start her up, slow crank for a few seconds, and I thought it was going to turn over then CLICK, Click . Grabbed the DMM, 12.27V. I found yesterday the dang phantom draw was back at 2.2Ma, found it's likely sill related to the OPS or connector. I think I'm going to have to pull the connector and remove from the wire loom as far up as I can to see if the wire is burnt & shorted somewhere and I'm going to have the altenator tested because how is 2.2Ma draining all the CCA capacity in less than 24hrs?!?!?
Soooooo, I disconnected the Battery & OPS, pulled the wires out the loom as far as I could reach and the bare spot was re-exposed, even found another small bare spot on another of the 3 wires. I just left everything unplugged and ordered a new connector / pigtail.
Ran into a major stopping point. OPS Connector arrived, it came with 3 wires Orange, Tan, Tan/Wht Stripe. Connected Orange to Orange, the other two were a crapshoot given age, heat, wire discoloration. Connected the last two as shown below, before connecting the battery, connected the DMM in-line as to do the draw test again to test my repair and damn it, couldn't read the DMM as I started hearing this noise I couldn't describe, well humming or buzzing from the OPS? and of course I removed the DMM lead. Yes I could easily swap the two wires to see if there's a change but wanted to ask if all thirdgens (SBC 305's/350's) used the same long body style OPS w/ 3 wire connector? All of them Orange, Tan, Tan/Wht Stripe or some Orange, Tan, Grey? I could really use a hand...
Ran into a major stopping point. OPS Connector arrived, it came with 3 wires Orange, Tan, Tan/Wht Stripe. Connected Orange to Orange, the other two were a crapshoot given age, heat, wire discoloration. Connected the last two as shown below, before connecting the battery, connected the DMM in-line as to do the draw test again to test my repair and damn it, couldn't read the DMM as I started hearing this noise I couldn't describe, well humming or buzzing from the OPS? and of course I removed the DMM lead. Yes I could easily swap the two wires to see if there's a change but wanted to ask if all thirdgens (SBC 305's/350's) used the same long body style OPS w/ 3 wire connector? All of them Orange, Tan, Tan/Wht Stripe or some Orange, Tan, Grey? I could really use a hand...
Hi Ed,
According to the schematics posted on Austin Third Gen for 1990, it had the orange and grey for the fuel pump, and the tan for the gauge....
Looking deeper into it, it appears the 1989 and earlier used the tan/white where the 1990 was the first year for the grey. I hope this helps .....
Last edited by OrangeBird; Jul 27, 2022 at 06:43 PM.
According to the schematics posted on Austin Third Gen for 1990, it had the orange and grey for the fuel pump, and the tan for the gauge....
Looking deeper into it, it appears the 1989 used the tan/white where the 1990 used the grey. I hope this helps .....
Thank you a trillion. YES it helped. I ran out swapped the positions of Tan & Tan/Wht Stripe wires, no hum or nothing when doing the draw test before connecting the battery with draw at .47Ma... she started right up,. I'm done testing for the day, don't even have the energy to go back out to heat shrink and re-loom wires. I'll be sending the seller feedback because I had to put a piece of Grey Duct Tape around the Tan/Wht Stripe wire so I never forget that sumb!tch is supposed to be GREY as shown in my GMSM. They needed to advertise it as a 85-89 TPI Camaro specific connector, I even paid a few bucks extra because of how it was advertised lol, and lost a little blood on the install.
Last edited by 92RS-HeritageEd; Jul 27, 2022 at 07:25 PM.
Went out this morning, pulled the battery for charging. Charged on slow (2ma) until full. Went out, completed draw test... 0.00ma, I connected the battery and went back to work. Came out after work, she started right up. I connected my Battery/Alt tester and looks like the Alt is charging so as long as my official repair holds and no other components take a dump this should be resolved!
Happy hunting ... 
but the battery is new (stamped 03/19). I'll test the battery and assemble the test light.
Batteries are new but the alarm system is a constant trickle drain and will kill the batteries in a few weeks. If I need to let the truck sit for an extended period of time, I hook a smart charger onto the batteries and leave it plugged in. That way the batteries stay charged and when fully charged, the charger stops charging. If I forget to plug it in, it's even better than a security system. Can't start the truck, can't steal it. 
happened again! However this go round the car tries to start but doesn't. Best way i can describe it is from the key turn it sounds like it's going to fire but she just dies as she turns over. If you give it gas, it *tries* to run. In fear of damage, i didn't force it to run long. No SES light, not running long enough to log.
but I am happy it runs 
