The computer on my Allison 2000 transmission (2003 Holiday Rambler Neptune) just blew. Mechanic said he only found one code on it that indicated "low voltage." He asked if I'd had battery problems. I hadn't. However, now that I think about it, I have the RV in storage right now, so I've been turning off the battery cut-off switches for both the house and engine batteries. I'm talking about the switches located in the battery compartment. I've been doing this as an anti-theft/ anti-fire precaution. I have been turning the switches back on every month when I take the RV out for a drive to exercise the transmission, brakes, etc. Then I turn the switches off again for another month. Could turning these switches on and off be the cause of the TCM frying? I'm concerned because it cost me $2,000 dollars to fix and if I don't know what caused the TCM to fry, then what's stopping it from happening again? Any ideas as to how to keep this from happening again? Crazy thing is the RV, although it is a 2003, only has 40,000 miles on it. Allison mechanic said he's seen the TCM's last 700,000 miles. I'd like to know why mine fried so prematurely.

Electronics of any kind are generally much more reliable now than many years ago. However, it only takes the failure of one five cent component in the module to allow for the whole system to fail. Unlike thirty years ago when products were repaired at the component level, today that is very rare. The lack of trained technicians, the high cost of test equipment, and the economics of the business has led to a situation of just replacing the whole product. When was the last time a "good" television tech fixed your television or stereo?

Dick A wrote: When was the last time a "good" television tech fixed your television or stereo?Yep, they're pretty much ancient history.

Yours may not have been bad. It just may have been changed by a mechanic that used the "shotgun" approach to fix a problem. In other words, replace everything until it works. It is funny how a dirty connection can look just like a bad component. The difference is the time it takes to clean that connection or replacing a perfectly good component that will cost the customer several hundred dollars. The only way for you to tell is to keep the old parts and then reinstall that TCM after the vehicle is running properly to see if it is really bad.

A certified Allison repair center should be able to test the TCM by itself for you.

Was the low voltage error pending, or stored?Dealing with vehicle electronics is sometimes hard decision. Logically you should have the computer fully scanned, troubleshooted and confirmed. But such procedure can easy cost $300, while replacement computer board might be $100. So to some degree taking a risk in dropping part without full scan can be a good bet. Being mechanically inclined I become pretty good in car electronics as I could not stand technicians who would charge high hundreds or even thousands for computers, where $90 sensor was bad. Get 2nd opinion if you can, or make sure the shop will take the computer back when they misdiagnose.

TCM on Allison Transmission needed replacing. Why?

15 Replies

Kayteg1
Explorer II
Feb 05, 2016
Was the low voltage error pending, or stored?
Dealing with vehicle electronics is sometimes hard decision.
Logically you should have the computer fully scanned, troubleshooted and confirmed.
But such procedure can easy cost $300, while replacement computer board might be $100.
So to some degree taking a risk in dropping part without full scan can be a good bet.
Being mechanically inclined I become pretty good in car electronics as I could not stand technicians who would charge high hundreds or even thousands for computers, where $90 sensor was bad.
Get 2nd opinion if you can, or make sure the shop will take the computer back when they misdiagnose.
noteven
Explorer III
Feb 05, 2016
A certified Allison repair center should be able to test the TCM by itself for you.
rgatijnet1
Explorer III
Feb 05, 2016
Yours may not have been bad. It just may have been changed by a mechanic that used the "shotgun" approach to fix a problem. In other words, replace everything until it works. It is funny how a dirty connection can look just like a bad component. The difference is the time it takes to clean that connection or replacing a perfectly good component that will cost the customer several hundred dollars. The only way for you to tell is to keep the old parts and then reinstall that TCM after the vehicle is running properly to see if it is really bad.
gbopp
Explorer
Feb 05, 2016
Dick A wrote:
When was the last time a "good" television tech fixed your television or stereo?

Yep, they're pretty much ancient history.
Dick_A
Explorer
Feb 05, 2016
Electronics of any kind are generally much more reliable now than many years ago. However, it only takes the failure of one five cent component in the module to allow for the whole system to fail. Unlike thirty years ago when products were repaired at the component level, today that is very rare. The lack of trained technicians, the high cost of test equipment, and the economics of the business has led to a situation of just replacing the whole product. When was the last time a "good" television tech fixed your television or stereo?

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TCM on Allison Transmission needed replacing. Why?

15 Replies

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