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ROAD RAGE

Code #1488

9 posts in this topic

Been throwing the low voltage (1488) code, the batteries are new and the cables are clean and tight.Anyone have an idea where i need to look/go next to find the problem???The truck seems to run ok, Just like to find the problem so I can fix-it.Thanks Ed.

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Have you cleared the code just to see if it was a fluke or from a recent previous low voltage condition or is it new/ comes back after clearing?

Check the altenator fuse in the main fuse box under the hood just for giggles its the big fuse that screws in... (Held in by 2 screws) if thats good you may have to start checking the wireing.. i would probe the 12 volt supply going to the ecm, if thats good then check the 5 volt supply coming from the ecm if its under 5 volts and you have 12+ volts going in, the ecm may have a problem or there could be a short to ground in the wiring some where.. Mike has on his website 3 schematics that will help with the wire pin outs for the engine bay /ecm.http://mopar.mopar1973man.com/cummins/2ndgen24v/wiring/wiring.htm. also Here is another for the ecm http://mopar.mopar1973man.com/cummins/general/ecm/ecm.htm

---------- Post added at 10:02 AM ---------- Previous post was at 09:40 AM ----------

just a thought, is your grid heater cycling in the mornings and if so what does your voltage gauge do? if it drops down under 12 volts and stays a while then comes back up you could have a grid heater relay sticking and drawing the voltage down and giving you that code.. the 5 volt supply is directly related to the battery voltage going into the ecm, usually

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Grid Heater is cycling, Voltage drops, than when cycling is complete it's back around 14volt.Thanks,,, I'll clear the code again to be sure. thanks again.................

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Double check your grounds as well a weak ground lead can and will cause the very same condition. The master ground for the ECM is buried behind the starter but the code is most likely coming from the PCM...

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Check your relay for the grid heaters. Periodically when the weather turns cold my wife returns home in a panic with the check engine light on. It turns out that the grid heaters get stuck on and draw the system voltage down and latch the light and code. Once she shuts the engine down and I have checked it, all was well but I could tell that the grid heaters stayed on too long and caused the problem.

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Check your relay for the grid heaters. Periodically when the weather turns cold my wife returns home in a panic with the check engine light on. It turns out that the grid heaters get stuck on and draw the system voltage down and latch the light and code. Once she shuts the engine down and I have checked it, all was well but I could tell that the grid heaters stayed on too long and caused the problem.

I tend to forget about that because my grid heaters are disabled... I un-hook mine very spring and hook the up again in the fall of the year... But if the relay is sticking I would high consider replacing the relays soon...

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Been throwing the low voltage (1488) code, the batteries are new and the cables are clean and tight. Anyone have an idea where i need to look/go next to find the problem??? The truck seems to run ok, Just like to find the problem so I can fix-it. Thanks Ed.

You might try cleaning the ground to the body .

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Check the black/tan color wires of Connector 1 pins 31 and 32 for good ground... That is the main ground on the PCM... Check light green/black wire of connector 1 pin 2 for switched +12V power... Check red/white wire of connector 1 pin 22 for constant +12V power... Should be the same voltage as the battery for both of the above test. So for the key on measure your battery voltage and measure the pin of the connector and see if they match.

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Auxiliary 5 volt supply output is too low

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