Stopped working, changed batteries, the light came on then went off, does this when i take the batteries back out then replace them, the indicator light stays on for maybe 3 or 4 seconds.

No vehicle will start if the battery voltage is 11 volts or lower due to the EFI.

The Check Engine Light came on, so there are Diagnostic Trouble Codes (DTCs) to be read. The code tells the issue and the from there you can Google the fix. You need to find out why your battery was discharging and not being charged at highway speeds. A professional grade scan tool computer can also check the transmission solenoids as the scan tool is bi-directional. It can command a solenoid to operate and then verify that it did. It can also read historical data, what was happening when it stopped running. Limp Mode is just there to protect the engine from further damage. There is probably a sensor failing somewhere, although the battery depletion is a puzzle.

https://www.google.com/search?q=mobile+auto+electrician+near+me

https://www.google.com/search?q=2018+28Z+Thor+Motor+Coach+limp+mode

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sounds like a easy short ,start at fuses box work ur way towards the front lights

Did you try using another power cord to see if it starts? Could be a weak power cord or intermittent failing power cord.

Could also be a short in the system preventing power to flow through the laptop

The battery light only comes on to tell you that the BATTERY IS DISCHARGING with the engine running. The usual CAUSE is the alternator or battery cable connections, NOT the battery itself.

Please also review this article:

What Else Could Be Wrong?

If it works, yes you can. It maybe that the battery went dead.

Try removing the battery for 10 minutes and put it back and see if the laptop powers on. If it doesn't, connect the power cord and see if it is charging. If not, then most likely battery is dead.

You can buy batteries from stores like ebay.

Try and replace the cmos battery. Good Luck.

there is often a small back up battery in the immobiliser unit itself, if you can locate this unit and replace the battery with the ignition on / engine running, then it should not need recoding and work fine after that. The other thing that could be wrong is the key battery (if the fob has one) or the transponder chip in the key head. If the key signal is low the immobiliser lamp will light during driving, but this does not explain the alarm going off. That is more likely either a poor vehicle battery, alarm / immobiliser back up battery, or another electrical fault such as water leakage into a tail-light or even the alarm unit itself when it rains. A lot of alarms are voltage sensing and when the vehicle is parked they will alarm if the battery voltage changes for any reason, though not during driving so the battery in the immob is my first choice to look at.

hmmmm perhaps it may be the phone it self

Your indicator bulb has blown. If you replace the bulb, you would find it will go back to normal.