Letts alk about PATS

[tekrsq]

Let's talk about PATS issues with my 99 EB.

I have an SCT X4 on my truck with tunes from 5 Star Tuning. A little over a week ago, while trying to return the truck to stock, it had some type of error and would not let start the truck. It would crank fine, but the THEFT light on the dash was blinking rapidly, it would not start, and it wouldn't let me access any menus on the X4. Called 5 Star, they said to call SCT.

Got through to SCT, who went through my laptop to do whatever they do to the X4. The tuner seemed fine, and let access all the menus, but I couldn't download the stock tune because my battery was at 11.6. Charged the battery overnight, and able to successfully return the truck to the stock tune. Took the truck out for a test drive, and it stalled at a traffic light about 6 miles from home. Again, it would crank fine, but rapid blinking THEFT light, and no start. Got towed home. After getting off the rollback, I tried to start it, and it started fine....on the first try.

Drove it to work yesterday (60+ miles round trip). It seemed fine, but I noticed on the X4's voltage gauge, that while at STOP lights my voltage would slowly drop into the high 13's. Truck never stalled, but I would up the idle a little when I noticed the drop, and the voltage would go back up.

When I got home from work last night, I parked the truck, and attempted to restart it right after shutting it off. Same crap.... crank but no start and rapidly flashing THEFT light, and some kind of error code on the X4. It showed 14.3v on the X4 while running when I first got home, but only showed 12.0v on the battery when I checked it after it wouldn't start. Put it on charge overnight, and it started up fine this morning.

Does this sound like a PATS issue, or bad battery issue? When the truck wouldn't start, I tried my extra keys and got the same response. It would seem to me that if there is enough juice to crank the truck, it should be enough juice for the PATS to work correctly. I cant afford to throw a lot of parts/money at this thing right now, but I need it to get back to being reliable.

 

[Yupster Dog]

Put it on charge overnight, and it started up fine this morning.

Twice you put on charger and it was fine, you didn’t mention have you had your alternator checked?

 

[tekrsq]

Twice you put on charger and it was fine, you didn’t mention have you had your alternator checked?

Yeah. It's charging fine (14.6v) while moving, but the other night I noticed the voltage slowly dropping while at traffic lights. It got down to 12.1 a couple of times. So I broke down and had it checked. Auto Zone says it appears to have a bad voltage regulator, and not charging at idle. In addition, the battery failed the load test.

So, I know I have bad battery and alternator, but I'm still not sure this is the complete source of my issue. I find it hard to believe that a battery that is strong enough to crank the truck multiple times, is too weak to engage the PATS. I had a battery completely die on me a few years ago, and NEVER had any issues with the PATS. Regardless, I'm in the process of changing the alternator and battery (alternator arrived today), so hopefully I'll have these switched out this weekend, and see what happens.

 

[Yupster Dog]

So, I know I have bad battery and alternator, but I'm still not sure this is the complete source of my issue.

Until you Fixed Battery/alternator, trying to diagnose any further is a waist of time.
Inproper voltage can cause all sorts of problems.

Regardless, I'm in the process of changing the alternator and battery (alternator arrived today), so hopefully I'll have these switched out this weekend, and see what happens.

You already on the ball! Hopefully that's all it was.

 

[tekrsq]

Until you Fixed Battery/alternator, trying to diagnose any further is a waist of time.
Inproper voltage can cause all sorts of problems.

You already on the ball! Hopefully that's all it was.

THX !!!!

Got the alternator (160 amp) installed today, along with a new battery. Battery showed 12.5v before installation. With truck idling, and NO accessories on, both my DMM and X4 "voltage gauge" showed the truck charging at 14.5v....in both park and drive.

I drove the truck approximately 15 miles, with headlights, driving lights, front & rear HVAC units on. While moving, the X4 voltage gauge showed a constant 14.5v, and while idling at traffic lights a constant 14.1v-14.3v. I had no stalling issues, however, I did not stop to turn off the truck to see if it would restart. When I returned home, I shut off the truck, and was able to immediately restart it without any issues. X4 voltage gauge showed the resting battery at 12.4v. I rechecked the battery after 1 hour, and both the X4 and my DMM showed the battery still at 12.4v.

Throughout this entire ordeal, I have checked the truck numerous times for any parasitic draw, and none have been indicated....even with the X4 continuously plugged into the truck. I will continue to monitor voltage levels (at rest and driving) for several days before saying this issue is fixed.

I double checked all the cables, wires, etc and everything looked to be in good shape, but when spring gets here I think I'm going to upgrade the positive cables and add some heavy duty grounding cables (in place of the OEM straps).

I'm scared to attempt to change tunes with the X4, but I might try in a couple of days if there aren't any other issues.

 

[Yupster Dog]

Throughout this entire ordeal, I have checked the truck numerous times for any parasitic draw,

I double checked all the cables, wires, etc and everything looked to be in good shape,

Sometimes when there is a bad conection it will allow draw from the battery but won't let the charge thru to the battery. There is a easier way to make sure all connections and cables are good.

Voltage Drop Test is testing the connections without having to take them apart and you can work your way right to the problem.
So you have a digital volt meter($15@walmart) and you put the red on the positive battery post and the black on the negative post you will get how many volts your battery is putting out. (12.v)
now that you know your digital volt meter is on and working,



The goal is to read 0 volts.(means all good connections) the more volts you read the worse the connection. (Ex 1.5v it's a little dirty all the way to 11.3v means almost no connection.)

(notice i dont say black and red colors here, that is because it doesnt matter what colors where)

Put one wire on negative post then put the other wire on the clamp that is on the negative post. If you read any volts at all those volts are being lost in the connection from the post to the clamp. (Ex if you read 1.5v you need to clean the battery terminal). put back together and move on to the next connection on the wire and one still on the battery post.
This can be done on both positive and negative sides the exact same way.

Look up (Voltage Drop Test) You tube vids get a little techy but my explanation should help a little.

 

[eyearemekanik]

Are you sure your truck is properly set back to stock? The PCM may not be properly commanding the alternator. The PCM determines the operation of the alternator depending on the current load. Could still be voltage loss / parasitic draw but I would also look at the pids for the alternator too.

 

[tekrsq]

Sometimes when there is a bad conection it will allow draw from the battery but won't let the charge thru to the battery. There is a easier way to make sure all connections and cables are good.

Voltage Drop Test is testing the connections without having to take them apart and you can work your way right to the problem.
So you have a digital volt meter($15@walmart) and you put the red on the positive battery post and the black on the negative post you will get how many volts your battery is putting out. (12.v)
now that you know your digital volt meter is on and working,



The goal is to read 0 volts.(means all good connections) the more volts you read the worse the connection. (Ex 1.5v it's a little dirty all the way to 11.3v means almost no connection.)

(notice i dont say black and red colors here, that is because it doesnt matter what colors where)

Put one wire on negative post then put the other wire on the clamp that is on the negative post. If you read any volts at all those volts are being lost in the connection from the post to the clamp. (Ex if you read 1.5v you need to clean the battery terminal). put back together and move on to the next connection on the wire and one still on the battery post.
This can be done on both positive and negative sides the exact same way.

Look up (Voltage Drop Test) You tube vids get a little techy but my explanation should help a little.

I did it on both positive and negative sides. Every connection between the neg terminal to block, block to frame, and block to firewall read 0.01v. I got the same 0.01 from the pos terminal to starter, alternator to starter. The battery was sitting at 12.1v this morning, but it hasn't been ran for 2 days. The truck started fine, and still charges at 14.5v at idle, and 14.2v-14.6v while moving.

Are you sure your truck is properly set back to stock? The PCM may not be properly commanding the alternator. The PCM determines the operation of the alternator depending on the current load. Could still be voltage loss / parasitic draw but I would also look at the pids for the alternator too.

I'm not 100% sure, but I can only go by what the tuner says....and the tuner says it's back to stock configuration. I've been scared to try another tune until I can positively say I do not have a voltage issue.

 

[EngineerMike]

A new battery at 12.5 run 15mi on a new alternator that ends at 12.4v is not right. I'd conclude a problem with charging, bad new battery or bad connections which you seem to have eliminated. Also, 12.1 after 2 days indicates parasitic draw or a bad battery.
I got tired of batteries dying prematurely so I've unplugged the battery charge sensors on my cars so the alternator runs at full voltage by default; my Nissan pickup ECM e.g. dropped charging to 12.3v running from 13.8 at startup which won't maintain a good battery & kills it in about 2 years. But you report 14.5ish running so that doesn't appear to be your problem.