2003 Jeep Grand Cherokee Amp draw on chasis

Tiny
TSAYERS
  • MEMBER
  • 2003 JEEP GRAND CHEROKEE
  • V6
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
I bought the GC for my daughter knowing a few electrical issues existed. That being said, I changed the battery and tested the charging system (which is putting out 14.05 VDC). My question is. When I turn the car off and remove the key from the ignition I am getting 11.5 - 13 Amp draw. I'm reading this across the positive terminal and a bolt head on the chasis. I have removed each fuse and relay in the engine compartment and under the dash while watching for the draw to disappear, which it hasn't. Any further direction would be greatly appreciated.
Sunday, March 22nd, 2015 AT 7:00 AM

7 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
LIGHT UNDER THE HOOD ON?

YES, YOU PROBABLY THINK THAT WAS A STUPID QUESTION

I'VE SEEN ALTERNATORS BLEED A BATTERY DOWN DUE TO DIODE ISSUES

SNATCH ALL THE WIRES LOOSE FROM IT AND SEE IF IT DROPS TO A NORMAL ACCEPTABLE AMP DRAW LEVEL

IF IT IS SUSPECT, SNATCH IT COMPLETELY OFF AND HAVE IT BENCH TESTED

KEEP US POSTED ON PROGRESS

BOUGHT JEEP # 7 IN 1991, DAUGHTER, AT ABOUT AGE 3, AIDED IN RESTORATION

AFTER USING HER BIRTH-DATE FOR THE HOOD NUMBERS SOMEHOW "WILLY" BECAME HER NON-SELLABLE BUDDY AND INHERITANCE. SEEMS I HAVE NO SAY SO IN THE MATTER. AT AGE 10 SHE WAS PROFICIENTLY DRIVING HIM AND PERFORMING REGULAR MAINTENANCE

SENDING PICS FROM DAY ONE, DURING RESTORATION, AGE 4 ALMOST 5
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Sunday, March 22nd, 2015 AT 7:54 AM
Tiny
CJ MEDEVAC
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  • 11,004 POSTS
AGE 10 (PROFICIENT), AGE 25 W/ GRANDSON, GRANDCHILDREN AND MY DOG (MOST RECENT "WILLY PIC")

WE ARE STILL SORTA DOING UPGRADES TO HIM!

LAST PIC, IS MY '77 CJ-5 MY DAILY DRIVER (LAST OF MY SIX CJ-5s, "MR. JEEP" WAS PURCHASED IN 1991 A FEW MONTHS AFTER "WILLY") I'VE OWNED/ DRIVEN NUTHIN' BUT JEEPS SINCE I WAS ALLOWED ON THE ASPHALT IN 1981

THE MEDIC
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Sunday, March 22nd, 2015 AT 7:55 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
This is a different expert. I'll try to offer you a little more than "is the hood light on?"

What you are doing is not measuring current draw. It sounds like you are simply measuring battery voltage. If you really had a current draw of that extreme it would be from something very obvious and would kill even a new battery in a matter of hours. That would be enough current to operate nearly every light in the vehicle simultaneously (minus headlamps).

Here is the correct way to test for current draw.

You will need a digital ammeter and a jumper wire with clips on the ends to do this.
First rig any door switches so you can have a door open without triggering the interior lights and unplug the hood light. Remove one battery cable and attach the meter in series between the battery cable and battery post. Take the jumper wire and also attach it the same way. Leave the jumper wire on for at least 15 minutes to expire all the automatic timers. Now remove the jumper wire and read the meter. Anything over 50ma (.050A) is too much draw. The way you locate this is to start removing fuses one at a time until the meter drops to normal level. This will be the circuit with something staying on. Determine what components are part of that circuit and check them individually until the problem is isolated.
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+1
Sunday, March 22nd, 2015 AT 8:24 AM
Tiny
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Just to eliminate any confusion on my end. I kept the battery hooked as if in normal operation and connected my meter to the positive post and a good ground on the chasis. The key was not in the ignition at any time during the process. And all doors were closed, so no interior light would give me a false reading when the engine compartment. I pulled the fuses in the engine compartment one at a time and replaced them after reading the meter. I did same in the cab with the exception of the driver door being open. I can recheck these later today with verification of the interior light removed.

I have numerous forum entries about screws for the PCM board screws stalling the engine, but am leaning away from that as I don't have any issues when driving. Yet.

1. Should I leave fuses out after I remove them, so not to miss a partial ground or small amp draw?
2. With regards to the above response, if diodes are bad on the alternator, could it draw amperage back through it?
3. Lastly, does it the meter have to be in series with the battery to get a correct reading for amp? Or the way I decribed doing the same thing?
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Sunday, March 22nd, 2015 AT 10:15 AM
Tiny
WRENCHTECH
  • MECHANIC
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You are not measuring current draw that way. There is no point in looking for anything until you start measuring correctly.

Unless you are using an induct5ive pickup which wouldn't be sensitive enough here anyway, the circuit needs to be interrupted to measure current flow. The meter needs to be part of the circuit.
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Sunday, March 22nd, 2015 AT 10:20 AM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
IN PLAIN JANE LINGO,

HE MEANS SNATCH OFF THE NEGATIVE BATTERY CABLE

HOOK ONE LEAD OF THE METER TO THE NEGATIVE BATTERY POST AND THE OTHER TO THE LOOSE CABLE

YOU SHOULD SEE CHANGES NOW IF YOU PULL A FUSE WITH ANY DRAW (EVEN ACCEPTABLE DRAWS, LIKE THE RADIO MEMORY)

THANKS WRENCHTECH, I DIDN'T PICK UP ON HIM GOING TO GROUND WITH THE METER

KEEP US POSTED ON YOUR NEW FINDINGS

THE MEDIC
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Sunday, March 22nd, 2015 AT 3:19 PM
Tiny
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OK guys, here's what I have for ya. With the meter in line I had an 11-12 amp draw. I removed the fuses, in the engine compartment, one at a time and noticed that on a few of them that the draw would immediately drop 6-8 amps. This happened on 8 different fuses (I'll list them below). I did replace them to see if they would show the draw again--which they did. I have left them out of the fuse box to do some research online and get y'all's take.

With those fuses removed, I connected the negative battery lead and let anything else in the car go through their draw for five minutes or so. I started this with a 4 amp draw and after the five minutes rechecked it and it was showing 0.1 amps.

Looking for this issue previously, I found that GCs (and Jeep vehicles) have had issues with the PCM grounding out because of the board screws being too long. I found this right here on 2carpros forum. I'll see if I can locate it again. The post wasn't about and amp draw, but a stalling problem. I'm trying to locate a schematic as well, not just the generic ones in my Haynes manual.

Here's the list of fuses; with position in the box, amperage and name for the fuse:
Position 3: JB power lamps 50A
4: ABS pump 40A
8: ignition/starter 40A
10: radiator fan 40A
12: JB power 50A
15: JB power 50A
19: PCM battery 10A
25: ABS main relay 20A
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Tuesday, March 24th, 2015 AT 2:14 PM

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