Whole vehicle current Draw????

[FMROB]

Well, I have a problem with dead batteries (twice). Not the altenator, new batteries (they tested okay), and charging system and all connections a-ok.

Measured the current draw of the vehcile with everything off (inc. dome lights) The only thing that should be running is the memories for the equipment in stand by mode, nothing powered on.

After measurement I am at about 2.5 amps. After throwing the main (aftermarket) disconnect I measure the vehicles "OEM" current draw at about 1.5-1.65 amps. After re connecting my equipment and systematically pulling the fuses for the radios my mcs2000 appears to be making the difference from 2.5 amps to about 1.7-1.85 amps.

Question: What should the "OEM" virgin current draw be for a yukon xl or any vehicle for that matter.

Thanks, Rob

[EOppegaard]

To me...the only things that should be drawing power should be the memories for the clocks, as well as the onboard computer memory...however the power consumption should be an amp...max (I guess) There is no need to have a large current draw for these things.

Is there something that may be hardwired that you are forgetting? Such as a radio charger, or a flashlight charger, or the like?

[tvsjr]

Something's wrong. Figure the average car battery is 60Ah (at C, but who's getting picky)... 1.5amps would totally nuke the battery in just over a day (you wouldn't be able to start it within 16 hours, most likely.) You should be pulling milliamps with everything functioned off.

My current draw (with the GPS staying hot) is about 300mA... undetectable if I kill the GPS. Full-on current with all lights, radios, and keyed down on a 110-watt radio is 97A.

[Max-trac]

Yea, something is wrong, should be milliamps.
Glove box light or something?

[mikeh]

mcs2000.... do you happen to have a MTVA installed?

[EOppegaard]

mcs2000.... do you happen to have a MTVA installed?

That's what I am thinking, there has got to be something else drawing some juice...something couldn't be grounding out somewhere could it?

[T-POWER]

Hi, Your Yukon draw should be no more than 40ma if you have the factory recomended battery in capacity.

To test the truck per the GM Service information you need to install the amp meter between the battery and the neg cable. You need to use disconnect adapter cable that you can open and close as the neg battery cable between the battery and the neg vehicle cable.

With the adapter cable installed and in the run position go drive the truck for 5 or so miles to let the On-Star if you have it, you did not state the year of your truck, get its gps signal. turn on and off all the systems in the truck than park and remove the keys and shut the doors.

Install the amp meter between the two halfs of the adapter cable and open the circuit with the amp meter as the return.

After 20 minutes see what your draw is. 40 ma or less is ok. The On-Star will come up to high power every hour in its cycle to check for messages from On-Star, but dont mind this unless it never goes to low power mode.

Hope this is written so its clear, if not let me know and I will see if I can send you the SI documents from GM. I work for a multi-line GM store in the service dept. We do a lot of battery draw tracing.

Dale

[FMROB]

Guys, Thanks for the reply. The truck is a 2001 yukon xl 2500 series vehicle.

I just can't imagine the current draw being in ma. The average maxtrac at idle draws about 500 ma, so if you had three at idle you would have 1.5 amps current draw.

There are no flash light chargers, radio cahrgers, on star etc.
Here is the equipement list.
1) Mcs2000 uhf III set to a 2hr time out from last use
2) spectras 800/vhf both on ignition
1) syntorx9000 lowband on ignition with VRS and siren
1) Whole crap load of lights and strobes connected to relays operated by the spectra switch panel which is master relay switched thru ignition.
1) Sony xm radio reciever on ignition.
1) Nextel cradle/spk phone/chrager on ignition.

SO, as you can see everything is off when the ignition shuts off, except whatever current is drawn by the following items..
1) Factory am/fm radio
2) factory security system
3) on board computer
4) all four moto radios keeping the scan lists alive

Any other ideas. Also , the gentlemen mentioned to measure the current draw over the negative line, I have done so on the positive line. Is that a problem??

Thanks, Rob.... Happy New Year.

[nmfire10]

Something is not turning off. Check the underhood and glove box lights. Since you can't really see them with the hood/glove box closed, pull the bulbs and see if the draw goes away.

The only other way to do this is to start pulling fuses on your extra-cirricular devices (lights and radios) and watch the meter. At some point, you will pull a fuse and it will drop back to normal. That one is your culprit.

[Pj]

I think you said it...but you disconnected EVERY aftermarket product? Aftermarket alarm system?

With all my toys plugged in and off, I have a nice little current draw (3 spectras, 1 x9000, GPS, lightbar blah blah).

If I let the truck sit for a few days, I will have a problem. Pull my AUX fuses where everything is connected to, I can let it sit for a few weeks and start on 1st try..

I'd have to say there must be some little thing being over looked, or not wired correctly somewhere....

[T-POWER]

Hi Rob.


The 01 Yukon will power down to the 40 ma if everything is working properly.

If you disconnect all aftermarket equipment, install the amp meter in series in the neg cable and let the truck sit for 20 minutes, and the draw is above 40 ma you need to go and start pulling the fuses from the underhood fuse center 1 at a time (dont put the fuses back in) untill you find the 1 that the causes the draw to come down to 40 ma or less.

Yes its a pain in the arse I have been down this road many times.

The new GM trucks have many controllers in them. From the pcm to modules for body, door lock/window module, seat modules for the power seats and the list goes on.

I have a 96 Chevy k1500 with 3- Syntor X 9000, 1- 900 mhz Spectra and a Kenwood V7A.

Good luck and a Happy new year to all

Dale

[ASTROMODAT]

If your current draw is more than about 10-20 mA, then as Dr. Lee would say: "Sumsing wong, sumsing vahry, vahry wong here!"

[apco25]

My truck is loaded to the gills with equipment and I don't have any excessive amp draw issues.

I can let the truck sit for days and it will start right up with no problems.

[ASTROMODAT]

You should be able to go on a trip, come back 30 days later, and start your car up very easily. Anything short of this means you have a sneak current somewhere, a bad battery, and/or a bad alternator. I think you are in serious denial.

[Alan]

SO, as you can see everything is off when the ignition shuts off, except whatever current is drawn by the following items..

4) all four moto radios keeping the scan lists alive

Well that is a major part of your problem right there. You can't run 4 Motorola (or any brand) radio's hot all the time and expect the vehicle to start after about 20 hours.
I would sugest a device such as the "Power Tamer" to shut off the radio's after a couple of hours.

I concur with the other postings on OEM current draw. We recently had a problem with a new car with a dead battery after 3-4 days. Traced it to the CDPD modem. It drew 0.4 amp. That was enough to kill the battery over several days.

[hooknladder]

I use a constant duty solenoid to power my Maratrac and Maxtrac. I put a HD toggle switch in line with the ignition sense wire to the solenoid so I can listen to the radios without having the keys in the ignition. I just simply throw the switch under the dash when I'm gonna park it for the day and have never had a problem.

[FMROB]

Maybe I should clarify.

The radios are not "hot all the time" as in they stay on and operating when I shut the car off.

The radio are all hooked up correctly with the main power being hot all times, and all ignition wires being hooked to ignition to allow all radios to turn on and off when you use the vehicle.

All of the radios with the exception of the mcs need to be hooked this way if you want it
A) Operate on/off with hitting a million power buttons when you get into the vehicle.
b) Keep all the scan lists in order
c) keep the channel status and last used status correct.

For example, If the syntor does not have B+ current at the main power cable and the green wire (if I recall) and the radio is cycled on/off with the orange cable it will spaz out and loose the scan list and the last channel you left it on.

I will keep plucking around.. Thanks, Rob

[metro121]

You are pulling current from some or all of the radios even when you shut off the ignition.

Even when you use the ignition wires from the radios for power up and power down , you are still drawing an excess amount of current because the main hot and ground are still connected.

My guess would be from one of the Spectras. This is sometimes caused by trying to hack the radio via lab to get more features.
It sometimes causes the MLM to do something like continuously transmitt an emergency or auto affiliate when the radio has been turned off, (or you think it has been turned off). The other problem you may have is in the PA amp . This is a problem with Spectras and Syntor X9000,s. The PA amp may have a bad circuit or a short causing one of the exciters to stay in a continuous tx loop.
You can check this problem just by feeling the heatsink with the radio off. If the heatsink is warm you found the problem.

The last thing you can check for woudl be in the command board. The audio amps somtimes do the same thing as the PA amp. If the side of the radio is getting warm , then you may need to replace the command board.

[ASTROMODAT]

Another outstanding example of why hacked eBay radios, and/or parts built hogs, often times have these insidious demons. One should be able to have half a dozen Spectras hooked up with simply their normal ON/OFF power button to cycle them, with no need for a pseudo master switch. What a pain to have a separate power buss switch to the radios. I agree with the posts saying this is completely unnecessary. Look to your radios for the source of this unnecessary/improper power draw when their PS is OFF, and/or look to your vehicle for a power problem of its own. Sumsing wong here, sumsing vahry, vahry wong!

larry

P.S. One thing to be very leary of is that SyntorX. They can draw almost 800 mA on standby (receiving with no signal present), as their early synthesizer circuits were very power hungry. This alone would be enough to kill a typical car battery in about 36 hours or so. You should try an experiement by turning the SyntorX OFF, with everything else as is, and see if that doesn't give you a dramatic change. I bet it will.

[T-POWER]

Document ID# 887366
2001 GMC Truck Yukon XL - 4WD


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Battery Electrical Drain/Parasitic Load Test (w/ BCM)
Tools Required
J 38758 Parasitic Draw Test Switch
J 39200 Digital Multimeter
Battery Electrical Drain
If the vehicle exhibits a low or dead battery after an overnight period, or discharges over a period of 2 or 3 days, the electrical system should be checked for an excessive electrical drain. This is referred to as Parasitic Current Drain.

If a battery needs recharging and no cause is evident, check the vehicle for excessive parasitic current drain.

One or more on-board solid state control modules, such as the body control module (BCM) may at some time exhibit a failure mode that causes a high parasitic drain on the vehicle's battery. When the battery is disconnected to install an ammeter, etc., the excessive current drain may not occur once the circuit continuity is restored. Even though cycling the ignition key to the RUN and then to the OFF position may cause such a drain to recur, there may be drains that will not recur unless the vehicle systems are reactivated in a road test. Since the ignition switch must not be rotated to the ACCESSORY, RUN or START position with an ammeter installed between the battery terminal and the battery cable, a current drain test tool must be used as described in the following procedures.

Before starting this procedure, ensure that the ignition switch is in the LOCK position, all electrical accessories are turned OFF, the underhood lamp is disconnected, the door glass is open and the doors are closed.

Caution: Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

Notice: Do not turn the parasitic draw test switch to the OFF position with the engine running. Damage will occur to the vehicle's electrical system.

Notice: The test switch must be in the ON position when removing the fuses in order to maintain continuity in the electrical system. This avoids damaging the digital multimeter due to accidental overloading, such as a door being opened to change a fuse.

Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnect/Connect Procedure .



Install the male end of the J 38758 Parasitic Draw Test Switch to the battery negative terminal.
Turn OFF the test switch.
Install the battery negative cable to the female end of the test switch.
Turn ON the test switch.
Road test the vehicle while activating all accessories, including the radio and the air conditioning.
Turn OFF the ignition switch. Remove the key.
Important: From this point on, electrical continuity must be maintained in the ground circuit of the battery through the J 38758 in the ON position or through the J 39200 . The BCM can draw several amps of current after the ignition is turned off. Refer to Body Control System Description and Operation in Body Control System.


Install the scan tool and perform the power down now feature from the BCM output menu. After performing this function the scan tool can be powered off or disconnected, then wait an additional 5 minutes before continue testing.
Set the J 39200 Digital Multimeter to the 10 A scale.
Important: If an ammeter other than the J 39200 is used, ensure that the vehicle does not have a high current drain that would damage the ammeter when connected to the circuit. This can be done using the following procedure:


Connect a jumper wire with an in-line 10 A fuse J 36169-A to the terminals of the test switch.
Turn the test switch to the OFF position.
Wait 10 seconds.
If the fuse does not blow, the current is less than 10 A and the ammeter can be used safely.
Turn the test switch to the ON position before the fused jumper wire is removed and the multimeter is installed.
Connect the ammeter to the test switch terminals.
Turn OFF the test switch. This allows the current to flow through the ammeter.
Wait at least 60 seconds, then check the current reading.
When there is a current reading of 2 A or less, turn ON the test switch, this maintains continuity in the electrical system.
Then, switch the meter down to the 2 A scale, for a more accurate reading, when the test switch is reopened.
Take the reading in milli-amps.
Note the battery reserve capacity. Refer to Battery Usage .
Divide this number by 4.
Compare this to the multimeter reading.
The current drain should not exceed this number.
Example: If a battery has a reserve capacity of 100 minutes, the current drain should not exceed 25 milli-amps. If the vehicle has 2 batteries, add the reserve capacities together and divide this total by 4.
Important: If it has been determined that the OnStar is the source of the parasitic load, technicians should continue the diagnosis of the parasitic load test with the applicable diagnostic found in Cellular Communication. Refer to OnStar Battery Consumption Test in Cellular Communication.


Notice: Always turn the test switch knob to the ON position before removing each fuse to maintain continuity in the electrical system and to avoid damaging the meter due to accidental overloading, such as opening a door to change a fuse.

When the current draw is too high, remove the electrical system fuses one at a time until the draw returns to a value less than or equal to specifications.
Repeat the parasitic current drain test procedure after any repair has been completed.
When the cause of the excessive current draw has been located and repaired, remove the meter and the parasitic draw test switch and terminal adapters.
Connect the negative cable to the battery negative terminal. Refer to Battery Negative Cable Disconnect/Connect Procedure .

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Document ID# 887366
2001 GMC Truck Yukon XL - 4WD
This is from GM it may help, Dale

[FMROB]

Dale,

I must tell you... You must be one of the nicest people on the board. Between your answers and current research of my problem you have gone way above anyone I have seen.... I want to say thank you for your time and info, people like you make this board great. If there anything that you need ever pls pm me.

On a second note. The vehicle finally went to my local gmc dealer. That $2,000.00 extended gm warranty will finally get it's work out. I just didn;t have the time with my current work schedule to mess with it. I am going to drop this off to them first thing in the am on the way to work..

Thanks again dale... I will keep you posted. Rob

Happy New Year

[perthcom]

We discovered that CDM's would tend to come back on as the voltage dropped, even if the radio was turned off or was wired to follow ignition sense.
It wasn't unusual to come out and find the radio was ON even though we were paying explicate attention to be sure it was off the night before.
Since ChargeGard and Power Tamer doesn't cut off under low voltage until the battery reaches 10.5 volts (virtual dead battery) we designed our own 2-stage power-down timer.

Ours times down, or cuts off when there is still power to start engine. It also senses ambiant temperature so that in the winter you can still start the engine.

The 2-stages cuts off the ignition sense first (to allow current operational settings to be saved)... then a few seconds later cuts off all power to the radio. Upon engine start, the main power is applied, then Ignition sense.

We also designed it to consume only microamps when OFF.. so that when you return from your week in the sun in the middle of winter.. the vehicle will still start at the Park'n Fly!

[thebigphish]

We discovered that CDM's would tend to come back on as the voltage dropped, even if the radio was turned off or was wired to follow ignition sense.

we've noticed the same thing. Our road rescue had a CDM that would act erratically when the voltage dropped too low (ie, not follow IGN SEN, or even act conversely). It's latest / coolest trick is to "lock" itself on when shutting down the truck, and then hang until you disconnected the A+. nice trick. we love it.

if we had the time and money to refit the truck, we would...i HATE the electrical system on that piece.

[FMROB]

On the update!!!!!!!!!!

Truck delivered via tow truck on weds 11/5/05 to local GMC dealer.

It is now 11/11/05 and dealer has called saying that it was a bad BCM module, that they have replaced the BCM and the battery and are letting it sit over night to test.

I will update when I know further. See, I knew all along that it wasn't my stuff.


1-14-05:: Truck is back and working....... A bad BCM module, which is operated by the TBC "truck body computer" fuse in the under hood power dit. center.

[HumHead]

Not to hijack the thread too badly, but-

Does anyone happen to know the normal parasitic draw numbers for an Explorer (1998 to be exact)? The vehicle is sucking down around 170mA with all of the add-on equipment disconnected. The toys only add about 25mA more (unless the Streamlight needs a serious charge )

The battery is clearly going south, since it currently goes dead within 12-24 hours. I'm sure the shiny new Optima Red Top that it will be getting tomorrow will help, but the math on 200mA parasitic draw still isn't that impressive.

Thanks!

[chiefhal3]

Don't forget to disable the hood light when checking all this.

[KuhnElectronics]

I have traced a few dead batterys lately and it seems that people with 2 or more strobe packs are drawing current constantly even if the strobes are not activated. For instance take a Whelen 90 watt 6 outlet, and wire it directly hot, and then switch strobes 1 & 2, then 3-6. I was showing a large current draw coming from the packs even not being powered on.

Nick

[chiefhal3]

When I layout an installation project I normally plan to put all items that are normally hot on a relay that is hooked up to either a master switch or the ignition/accessory switch depending on application. This includes items like strobe power supplies, cell phone amplifiers, even cd changes and stereo amplifiers. The only power leads that I hook up direct are the main power feeds to transceiver radios most of which now a days have a switched feed to turn off and on. I have never seen any noticable load on any motorola radios connected in this manner when the switched lead is off.

I have also on power supplies that were single purpose put both the power lead and the switch lead on the same switch. Doesn't ever seem to be a problem. If you are wanting to be able to switch front or rear or some combination independantly then the first example is best.