My name is ***** ***** I will assist you.
Your transmission will have a temp sensor on the top tide of the valve bosy. I highly suggest taht if you are not Allison trained or never took one apart, don;t attempt to do the swap of the sensor yourself. I would have a Allison shop do it.
Here is why, to get to that sensor, you have to pull the transmission and roll it upside down. Then you need to remove the valve body. On the valve body, there are 3 bearing balls in there. If you drop one or misalign them, the transmission will not shift and you will burn out a clutch in minutes. I know for I made this exact mistake myself. Hard lesson to learn. You can drop the valve body while installed, but there is a $5,000 tool that is needed to get it to align back up properly. Most people don't have that tool for they don't do Allison's every day to need one.
With that light being on, even on a cold engine, most likely that sensor is bad. The sensor reads through the main harness that goes into the transmission. The signal is sent from the senor to the TCM (transmission module) and then to the vehicle chassis module on the bus in which it will light up that light.
I know you were hoping for a simple fix for the light, but there just isn't one.
At least now that you know what you need to do, you can move forward as needed.
I don't know why Allison said there isn't a temp sensor for there is one. All of them have it. There may not be an external gauge sensor, which is what they are thinking of, but it has an internal temps sensor for that is how the transmission controller knows how to do the shift point for smooth shifting of the clutches and how much engagement is needed on the solenoids as well at what RPM to shift at due to the temp of the transmission fluid.
CLICK HERE for a troubleshooting manual, if needed.
You want a 5 star service and I want to provide a 5 star service. Please consider that I don't know your skill level as well as I can't see,
touch, smell, hear, or taste the vehicle/machine in question. Please provide as much detail as possible and I will provide as much back.
The system DOES NOT automatically give me credit from your deposit. A rating is REQUIRED. You are rating me for the information I provide,
not the website. I have no control over the site fees, site errors, category errors, or how long it took for a response for these reasons.
I am not an employee of this website, so please rate with a POSITIVE (green) rating for me to get credit for assisting you. You still pay
the website for negatives or by not rating at all. I just get nothing from that payment you made. So please rate each answer I provide.
I want you pleased with my service to you so please inform me before rating negative (red) and I will do my best to make it right. Follow
ups for same question are always free after ratings have been made.
I do have many workshop manuals, diagrams, etc that I pay to get access to out of my pocket. If one is needed, please ask and I will give
you an offer at my technician discounted cost to you for such manuals. I never charge above that cost.
Thank you for allowing me to assist you through Just Answer!