Parasitic Drain

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Parasitic Drain

Postby Keys85 » Thu Mar 30, 2017 7:55 pm

I have a '84 S10 with 355 swap. The parasitic drain will kill the battery within 2 days or so. I measure it at .5amp. I located two orange wires, that have been connected to the + post of the alternator. With everything off....when you touch the wires to the post it actually sparks, so the power consumption is quit high. Looking at wiring schematics, it appears those two orange wires go to the ECM. I have most of the dash apart, but have not gotten the ECM out yet. With the two wires disconnected, I have no power to ignition, my fans, dome lights.... I'm not quite sure what can be sucking up the juice. I'm thinking, perhaps a bad ECM? Something not wired correctly...I don't hear any relays clicking when connecting/disconnecting the wires. It is not my stereo giving parasitic drain. I started tracing it by pulling fuses. Only found it when I disconnected these wires. Thought maybe alternator diode went out and was reverse feeding.

The only things that get power on the truck are exterior and interior lights, electric choke, stereo, wipers, horn, electric fans (manual switch to turn on). I will continue to investigate further.
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Re: Parasitic Drain

Postby lowblazin94 » Thu Mar 30, 2017 8:20 pm

Pretty much most of that is through the steering column. Rip the ECM out if you aren't using it. Get yourself a wiring diagram and study it til your eyes bleed. You can trace the wires to the fuse panel and eliminate from there.
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Re: Parasitic Drain

Postby Keys85 » Sat Apr 01, 2017 4:22 pm

I have done so. I have the dash completely apart. I have traced the parasitic draw to the 20A fuse for Horn/DM. Horn relay works. If I unplug horn, still pulls power. There's something else on that Horn/Dome light fuse block. It's not a direct short to ground. And whatever it is, it's factory. Nobody just jammed in some extra wire in there. I have been studying the schematics. I will find it...
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Re: Parasitic Drain

Postby lowblazin94 » Sat Apr 01, 2017 5:04 pm

Does the dome light work?
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Re: Parasitic Drain

Postby Keys85 » Sat Apr 01, 2017 6:26 pm

Yes, the dome light works. I think I have the problem solved, however, there is still a mystery. The Horn/Dm fuse is SHUNT to 3 other wires (orange). I began unplugging each wire off the shunt one at a time until I found the one that was causing the power draw. Now, I can't find an exact wiring fuse block for an '84 S10, or an '87, but I have found several fuse box diagrams for various Chevy's at the time - I'm sure they all used the same fuse box, just wired up the way that model truck needed to be.

I assume the '84 Chevy did not have a cargo light. 1 shunt wire must power the DOME Light, maybe one powers the glove box light (didn't check because I had it all apart - getting dark and getting cold). I left the wire causing the draw unplugged. It is not a direct short to ground. I'm looking at the diagrams here for various trucks. I see HD lamp wiring, courtesy lamp, clock, lift gate release. I'm really curious as to what is on the other end of that wire. Truck does not have a clock. There are no courtesy lamps (visor or rear view), obviously doesn't have a lift gate.

Truck does not have power windows, locks, rear defogger. When connecting this wire that is pulling power I don't hear a relay of any sort click......I really wonder where it goes!!! I'll eventually figure it out. It is a factory wire too, not something some kid spliced in. His work (wiring up the electric fans, radio...you can tell he hasn't played with wires before) and I plan to clean it all up and make it neat. While I have the dash all apart I'm going to T-in a vacuum line so my heater can blow from defrost to the vents/floor.
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Re: Parasitic Drain

Postby lowblazin94 » Sat Apr 01, 2017 7:19 pm

I'll look at the diagrams I have tomorrow. They might go back to 84. Glad you are getting it sorted out.
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Re: Parasitic Drain

Postby Keys85 » Sat Apr 01, 2017 11:43 pm

Greatly appreciated if you have a diagram for a 1984 and 1987. I think I may know what's going on, but, we'll see tomorrow perhaps. When I got this build, besides the cluster it came with, it also came with 2 other clusters for whatever reason. But since the VIN is '84, I'd probably figure on that one. I know that there was an option for a rear defroster and/or fog lights. I have neither, but doesn't mean they were never installed. I will have to look again. Perhaps that wire is feeding a relay for fog lamps....but, kinda high just to power a relay. And I would imagine the relay shouldn't be powered unless it is switched on, I have no aux switch for fogs or a defroster. I have also read the trucks may or may not have come with clocks.

I can't find a picture online, but, I have a setup under the dash near the horn relay and hazard flasher. The turn signal flasher is on bottom right of fuse block. There are some empty holes next to the hazard flasher - it is labeled buzzer. Not sure if there are two buzzers or one - one for door open lights on, the other for door open key in ignition. I'd like to get the proper buzzer in there while I got it apart.

I''m still using the ECM to operate the cluster. I may in the future build/buy cluster set up and eliminate the stock cluster, with gauges to match my tach. There is a white plastic box attached to the ECM which I think via looking at photos is a timer delay for courtesy lights. I don't have a switch to adjust the delay if that be the case, needless, it doesn't work. I only have a parking light switch, headlight, and dimmer. Lights go on/off when you open/close door. They do not stay lit. While I'm in there I also plan to Tee in a vacuum line which I don't think is there, to able to move the heat from defrost to vent/floor. I am also going to replace cluster bulbs that are burnt out and/or use schematic and fix what may not be wired correctly to have all indicator lights work. I know the bulb for my fuel gauge is burnt out, and seat belt light does not illuminate. Granted...seat belts don't appear to be wired. My parking brake light and check gauges light illuminate.
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Re: Parasitic Drain

Postby Keys85 » Sun Apr 02, 2017 9:04 pm

The orange wire causing the power drain follows a purple colored wire plugged into the fuse block labeled "clock". Obviously the clock the truck came with is no longer there. Ran out of time to dig deeper. Radio is removed. I would imagine the clock was somewhere rigged up in there. I just ran out of time to see where exactly the end of the wire goes. It must be running to something, or whatever circuit the clock was on, to be sucking juice. More digging.
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Re: Parasitic Drain

Postby bgblock427 » Mon Apr 03, 2017 10:28 am

This goes back to 86 but might help.
http://www.revbase.com/BBBMotor/Wd
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Re: Parasitic Drain

Postby Keys85 » Mon Apr 03, 2017 6:49 pm

Thanks. I have printed several pages of wiring diagrams and schematics. What I have is a Frankenstein. Although the VIN# is 1984, the dash appears to be 1987 with a 1987 cluster. I had a spare cluster. It is a speedo-cable type with a part # 25086195 and 26078792 on it. When I removed the cluster from the truck, I was expecting a speedo cable but it is part# 25085123 and 25083728. I ran the truck the other day with the ECM removed. Everything worked and lit up, except the speedometer. I realized that the cluster in the truck is run electronically. The DRAC or square module attached to the ECM I had unplugged along with the ECM hence is why the speedo didn't' work. I'm assuming this here https://www.google.com/search?q=25073960&tbm=isch&imgil=4xpPNfL3P9RgDM%253A%253BmnXvuUM4DTw6yM%253Bhttp%25253A%25252F%25252Fwww.ebay.com.au%25252Fitm%25252FDRAC-Speed-buffer-sensor-computer-module-88-93-GM-AGH-25073960-%25252F301168724979&source=iu&pf=m&fir=4xpPNfL3P9RgDM%253A%252CmnXvuUM4DTw6yM%252C_&usg=__w6gd8eTHKN4TkO-chqIpowStpYI%3D&biw=1440&bih=773&ved=0ahUKEwif4KrlyInTAhVLOyYKHVSnBP8QyjcIOA&ei=8OviWJ-oL8v2mAHUzpL4Dw#imgrc=4xpPNfL3P9RgDM: has something to do with it. Or was it for cruise control? It is AGH 25073960. Now...I don't know if the ECM must be hooked up as well to run the speedometer...but all the wires are there. If everything but the speedo worked, where all them wires going?

The two instrument clusters appear very similar but the lower lights (Service engine / Check Gauges / Brake / High beam / ..etc) are in slightly different locations. I know that when I set my parking brake that the brake light illuminates with the cluster I took out. But the other unit has said brake light in a different location. Would swapping them cause the wrong bulb to light??

Anyhow, its going to take a little time to sort out. I'd like to get a door buzzer and have that functionally work. Perhaps figure out the wiring for the seat belt light.
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Re: Parasitic Drain

Postby Rickracer » Tue Apr 04, 2017 4:52 am

That does look like a DRAC, and it WILL work sans ECM. I found out the hard way on my 93 that it won't run the RABS system alone though, but that's another story. 8)
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Re: Parasitic Drain

Postby lowblazin94 » Wed Apr 05, 2017 4:22 pm

I have the Chiltons manual that goes back to 92-83. 28860 is the number. I'm not able to scan the diagrams but hopefully that helps
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Re: Parasitic Drain

Postby Keys85 » Wed Apr 05, 2017 11:30 pm

Rick, what do you mean "run sans ecm"? My truck does have an ABS unit, appears to be wired up...but, I haven't dug deeper to see if they are functional. I would imagine there needs to be a pump motor or something, I don't see one. I haven't slammed the brakes on to find out. Personally, I don't care for ABS. If it is non functional, all the junk in their not working is coming out. I grew up my first car no ABS. I feel I have more control over a vehicle without ABS then with, whether pumping the brake, or steering the tail end with the throttle...etc. ABS in my modern cars have created stopping distances to be extreme. I feel I could have stopped some of my ABS equipped vehicles in a shorter distance had the rubber locked and slid on pavement. I have also found that ABS doesn't, by far, keep you from loosing your steering in a hard stop. Maybe a feature for a woman, new driver, kid, or "non car buff", but, I like my stuff olde school. And I like to have control over the vehicle, not a pulsating module. I have, unlike most drivers, taken vehicles out in empty lots, purposefully put them out of control, to feel how it reacts - oversteer, understeer...etc. Nobody does that. And they all have accidents. Never smashed up a vehicle.

Secondly...this DRAC module...do you think it will run the speedo without the ECM hooked up? I have also heard, inside, there are jumpers. You can swap the jumpers around should you change tires/gear rations. Check this out. http://tbichips.com/?page_id=504

The ECM I have pulled out is marked SERV. No. 1228062 86AMRW K391781649

If the DRAC will run the speedo, and the ECM doesn't do anything...lol where do all those wires plugged into it go? They can't be connected to any sensors they don't exist anymore. I see no point in putting the ECM back in if it's useless. Just extra weight. Lighter = faster. Faster = better.

Going to take me a few days to finish putting the dash back together. I just got busy with other things. My heat (defront) only vents to windshield. All the vacuum lines are there and appear to be hooked up. I imagine the vacuum source to control the pods is not connected and default to defrost. I'm thinking instead of installing a vacuum reservoir just supply the HVAC vacuum pods tee'd off the brake booster. Truck has great heat. Just maybe I would like it to blow out the vents instead of the windshield...As far as A/c...no...compressor is useless weight. Will take that out. Missing condenser and accumulator anyhow. don't need A/C for the toys. Ain't going too far with them on a regular basis...burned up a half tank of gas the other day and didn't go very, very far. But I'll admit...I did push the pedal down a little bit now and then. That carb SUCKS gas down like Miley Cyrus is in control of the venturis. Yet, it's tuned just right. Went through carb, power valves...vacuum...etc...it's set up the way it should be. Does richen up somewhat as one would like when the secondaries open. BTW, I think the cluster I took out was from a '86 Blazer. Like I said....Frankenstein. I want to go through that wiring myself, for my own peace of mind. I may have a rear end for it, friend of mind had called about, with the posi carrier already in it. Convert the rear to disc brakes...new bearings and seals and set of gears...should wake it up. It goes light hell already but I'm still breaking loose at 45mph. My friend wants me to go with a 4-link....I was thinking...caltracs and pulling the overload spring. All in time...Truck makes every other vehicle I drive feel like a wound rubber band is the powerplant.
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Re: Parasitic Drain

Postby Keys85 » Thu Apr 06, 2017 1:47 am

Curiosity got to me. I wanted to see what mem-cal and ecm was in there. The mem-cal chip is marked 9600. The board has the number 078081316499178. Couple numbers off the DRAC. AGA 25073960 and 25072570D. The 7-pin jumpers on the AGH from left to right (with pin out facing 12 O'clock) read as follows. I will use "i" for jumper and "0" for no jumper. I 0 I 0 I I I, according the website, with 3.42 gears input value is 0.773438. It appears they made these in 1991 withe 7 pin jumpers, 1994 and up use 14 jumpers.

I know the truck didn't come with stock tires I'm running in the back. Right now they are 255/60R15s, soon to be with new rims and some quality rubber, with a 26" tire, over the current 27".

Using that above link, the "input ratio" is calculated to 0.7973309598642672. Let's see what the chart says for the jumpers because the speedo has been dead on. Well...I found the jumpers set to an input ratio of 0.773438. Close, but not perfect. I checked speedo with police radar and it is spot on. Even factory P195/75R14 tires/wheels work out close enough.

However, when I switch to my 18" rims and I'm thinking of probably a 275 tire in the rear. 275/40R18 (rear) front (if they don't scrub - 235/40R18). This puts the input value at 0.8088694173460598, providing 3.42 gears. But I'm going to run 3.73s more likely than not, so,input value would now be 0.8821879902633927. (26" tall tire btw) Who knows that the OEM tires were...P195/75R15 or 205/75R15? 14" rim? The closest match I have found tire wise that mate exactly with 0.773438 use 225/60R16 tires, but there are numerous combinations and god knows it looks like two pins have been removed and soldiered. Either way...all that matters is they it works correctly with new rims and tires, and gears. Calculating input value for a 275/40R18 tire computes to, with 3.73 gears, 0.88218799026339. The pin out jumpers must be switched to this config as it's showing the closest value to 0.88218799026339 = 1 0 0 1 0 1 1 - We'll see what happens in time.
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Re: Parasitic Drain

Postby Keys85 » Thu Apr 06, 2017 1:53 am

forgive me if my calculations
are off any. I'm half asleep.
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Re: Parasitic Drain

Postby Rickracer » Thu Apr 06, 2017 5:59 am

I was not advocating for ABS, I am with you on my dislike/distrust of ABS systems, but I AM a fan of RABS, especially since I've done the LS brake swap up front, and prior to going to disc out back. The RABS system had never worked (activated) on my truck before I did the LS brakes up front, but once I did, the truck would actually transfer enough weight up front that the rears would now lock up. With RABS working, it would pulse the rear brakes enough to stop much quicker. The only hardware there is, is a pair of solenoids under the master cylinder, and the module beside it. But then I did the V8 swap, ditched the ECM, then discovered that the ECM did some calculating for the RABS module, converting the 4x signal from the DRAC to a 7X signal. Had I known that, I might have kept the ECM installed. One day, I will figure out how to feed the proper signal back to the RABS module and get that working again. 8)
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'93 S10 SB,RC, Comp XR276 Hydraulic Roller, Vortec head 363, 400 + hp, built 700R4, JW 2800 stall lockup converter, 3.73 posi, disc brake, narrowed 8.8 Exploder rear, LS Camaro front discs, Cal-Trac clone traction bars, Best N/A passes to date: 7.76 in the 1/8th, 12.24@109.27 mph in the 1/4, gonna spray it one of these days... :mrgreen:
76 Chevy Vega Drag Car, TWIN TURBO 355, P/G trans w/ brake and JW 4000 stall vert, 4 link back half, narrowed 9", 3.50 gears, 29.5x10.5W ET Drags. Best time9.669 @ 139.79, Latest video: https://www.youtube.com/watch?v=S59riYn ... ata_player
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Re: Parasitic Drain

Postby Keys85 » Fri Apr 07, 2017 12:57 pm

Front disc brakes were replaced with performance brakes. I forget now exactly what, maybe brembo or hawk or comparable manufacturer. They are really good. Brakes are powerful and will stop on a dime with all that cast iron up front. The rear still has the old drums in back. I have a friend looking into a rear-end for me, if it works out, it's already set up for disc and I will convert the rear to disc brake as well. Besides the ABS module next to the MC, I haven't dug hard enough to see if there are solenoids beneath, but I do see wires for wheel speed sensors going to the front brakes. While under truck, no wheel speed sensors for the rear. I would imagine for rear ABS there would need to be sensors for them? Eitherway...not a major concern of mine. Less parts = less things to go wrong.

Definitely will make a difference once I put the posi in. If I shift from 1st to 2nd and keep the RPMS in the powerband, pulls harder and accelerates harder/faster than anything my passenger has ever been in (and he's had a few toys in his day) and this is with breaking traction throughout 2nd gear. I think with the posi, let alone changing gears, getting the tires to bite in will only make it better.
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Re: Parasitic Drain

Postby Rickracer » Fri Apr 07, 2017 3:59 pm

RABS uses the speedo signal for the rear... 8)
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ASE Certified Master Automotive Technician (well over 3 decades of experience, :thumbup: )
'93 S10 SB,RC, Comp XR276 Hydraulic Roller, Vortec head 363, 400 + hp, built 700R4, JW 2800 stall lockup converter, 3.73 posi, disc brake, narrowed 8.8 Exploder rear, LS Camaro front discs, Cal-Trac clone traction bars, Best N/A passes to date: 7.76 in the 1/8th, 12.24@109.27 mph in the 1/4, gonna spray it one of these days... :mrgreen:
76 Chevy Vega Drag Car, TWIN TURBO 355, P/G trans w/ brake and JW 4000 stall vert, 4 link back half, narrowed 9", 3.50 gears, 29.5x10.5W ET Drags. Best time9.669 @ 139.79, Latest video: https://www.youtube.com/watch?v=S59riYn ... ata_player
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Re: Parasitic Drain

Postby Keys85 » Sat Apr 22, 2017 3:21 pm

Ok well, here's where we are at currently. Parasitic drain has been caused by the radio. I have since moved the wire causing the drain which keeps radio internal memory alive to the key-on ignition side. Fixes the parasitic drain...but not too much a biggie about loosing my radio presets. Who listens to the radio when you got a v8 Chevy with a cam in it?

Umm...it's been raining a lot. I'm not working in the rain. But I have found another problem I'm investigating. Wiper pump motor for the windshield squirter was left unplugged under the hood. I plugged it in to discover it is HOT with key on. My turn signal lever, also the high beam and wiper hi/low, all work. I am not sure if the washer function on the turn signal level is stuck or broken in the steering column or if there is something else not wired correctly/going on. I will be tracing out this mystery as soon as the rain stops.
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Re: Parasitic Drain

Postby lowblazin94 » Sat Apr 22, 2017 3:57 pm

There is one wire that is "spliced" in to the wiper switch.

It goes 12v to the switch and wiper motor. It is the wire that is the "home" power setting. Trace the wire and run that to a keyed 12v source. Trace it from the distribution panel and move it from there.
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