Amps at start-up - problem?

[Prospect62]

Volts at start-up - problem?

Hey guys,

I'm trying VERY hard not to classify this as a "problem" with my slick, black and beautiful new-to-me 2008 Ram. However as every day goes by, it irks me more and more.

When I first start my truck, the volt (battery) gauge stays very low and doesn't come up into the normal range for about a minute or so. And it's not a gauge problem, because the lights are dimmer and the HVAC fan blows slower until that gauge comes up to the normal range.

This happens regardless of weather conditions/temperature outside, and it happens when the truck is cold (sat overnight) or hot (I just shut it off).

I've noticed that the starter sounds slower than most Dodge's of this generation that I'm used to but the battery looks brand new and the dealer I bought it from said he himself replaced the battery when he got the truck a couple months ago.

I guess it's worth testing the battery and alternator but in the mean time, I was wondering if this condition sounds familiar to anyone here and if it's a common problem in this generation truck - like maybe it's a relay or wiring issue?

Any input would be appreciated, helpful or not! Thanks ya'll.

 

[justin13703]

Unfortunately on an 08 the voltage is regulated by the computer. So if there is a voltage regulation problem, chances are putting in a new battery or alternator won't change anything. I'm not exactly a pro on how it works so maybe an expert will chime in. I do know though, that on your truck the voltage is regulated by a computer in the truck, not the alternator.

 

[Harley Harrold]

Maybe this information will help.

OPERATION
The charging system is turned on and off with the ignition switch. The system is on when the engine is running and
the ASD relay is energized. When the ASD relay is on, voltage is supplied to the ASD relay sense circuit at the
PCM (ECM Diesel). This voltage is connected through the PCM (ECM Diesel) and supplied to one of the generator
field terminals (Gen. Source +) at the back of the generator.

The amount of direct current produced by the generator is controlled by the EVR (field control) circuitry contained
within the PCM (ECM Diesel). This circuitry is connected in series with the second rotor field terminal and ground.
A battery temperature sensor, located in the battery tray housing, is used to sense battery temperature. This temperature
data, along with data from monitored line voltage, is used by the PCM (ECM Diesel) to vary the battery
charging rate. This is done by cycling the ground path to control the strength of the rotor magnetic field. The PCM
then compensates and regulates generator current output accordingly.

All vehicles are equipped with On-Board Diagnostics (OBD). All OBD-sensed systems, including EVR (field control)
circuitry, are monitored by the PCM (ECM Diesel). Each monitored circuit is assigned a Diagnostic Trouble Code
(DTC). The PCM will store a DTC in electronic memory for certain failures it detects.

The Check Gauges Lamp (if equipped) monitors: charging system voltage, engine coolant temperature and
engine oil pressure. If an extreme condition is indicated, the lamp will be illuminated. This is done as reminder to
check the three gauges. The signal to activate the lamp is sent via the CCD bus circuits. The lamp is located on the
instrument panel. Refer to 8, Instrument Panel and Gauges for additional information.

 

[RonJon '06]

Definately a problem and as far as I know not that common. If it were me I would start by checking the battery, then the starter. A bad starter can draw a huge amount of current from the battery and I've read that bad starters can cause electrical issues on our trucks. If you have a voltmeter you can see what the alternator and battery are putting out for that first minute while the lights are dim. If both the battery and starter check out OK then I would inspect the PCM circuit board, they are not protected well from the elements and are prone to corrosion.

Also there is no ASD relay on the 2006 and newer, we have the wonderful TIPM.

 

[Harley Harrold]

Definately a problem and as far as I know not that common. If it were me I would start by checking the battery, then the starter. A bad starter can draw a huge amount of current from the battery and I've read that bad starters can cause electrical issues on our trucks. If you have a voltmeter you can see what the alternator and battery are putting out for that first minute while the lights are dim. If both the battery and starter check out OK then I would inspect the PCM circuit board, they are not protected well from the elements and are prone to corrosion.

Also there is no ASD relay on the 2006 and newer, we have the wonderful TIPM.

That is interesting, about the ASD Relay, since I copied my post directly from my 2007 service manual.

 

[RonJon '06]

[/B]

That is interesting, about the ASD Relay, since I copied my post directly from my 2007 service manual.

It looks like the service manual is correct, according to this the TIPM has an "internal" relay.

The Totally Integrated Power Module (2)(TIPM) is a combination unit that performs the functions of the Power Distribution Center (PDC) and the Front Control Module. The TIPM is a printed circuit board based module that contains fuses, internal relays and a microprocessor that performs the functions previously executed by the FCM. The TIPM (2) is located in the engine compartment, next to the battery (1) and connects directly to the B+ cable (5) via a stud located on top of the unit. The ground connection is via electrical connectors. The TIPM provides the primary means of voltage distribution and protection for the entire vehicle.
The molded plastic TIPM housing includes a base and cover. The TIPM cover is easily opened or removed for service and has a fuse and relay layout map integral to the inside surface of the cover. The TIPM housing base and cover are secured in place via mounting tabs. The mounting tabs secure the TIPM (2) to the battery tray mounting bracket (3).

 

[Prospect62]

Thanks guys, I'll get to checking the battery, starter and PCM.

I was completely leaning toward the alternator but apparently that's the least likely culprit?

 

[preachp]

Hi prospect,

Sounds like a dead or weak cell in the battery.
Had that issue on an 03 Sebring and a 14 Avenger.

preachp

 

[Prospect62]

Thanks I will check it!

 

[sylver91]

Most part stores and some shops offer free battery checks. When I do them I usually just load test the alternator anyway cause it confirms my diagnosis.

 

[Prospect62]

Thanks again guys. I haven't had a chance to get anything tested yet because I've been so busy. Truck seems to be fine except that one thing. I'll keep you posted.

 

[Prospect62]

Well in case anyone is following this, I replaced the battery and the starter over this past week and this issue still persists. Here we are nine months later from when I posted this and I'm not seeing any real drawbacks to this problem happening, but it's just annoying and making me very curious.

 

[sylver91]

Did you get the alternator tested? Why did you change the starter?

 

[Prospect62]

Nah never got that alternator tested. Seems to be charging fine once the gauge rises to the normal range. Lights are bright and all accessories work well. This always struck me as a computer issue and not a mechanical part like an alternator or starter, but at this point you're right - I should have it tested anyway.

I replaced the battery and starter last week when we had below zero temps for a few days and the truck wouldn't start. Turned out my starter was shot but since I bought the new battery anyway I'm just gonna keep it in there.