Block Heater causes Error Code

[dmlappert]

Just recently had a (the 1st) block heater cord installed. When I plug the block heater in, usually overnight, the next morning the engine light stays illuminated and an error code for "Battery Temp Sensor Failed" is presented. Replaced the sensors, but it continues to occur. This has occurred 3 out of the last 3 times the block heater was used... Any ideas?



2006 RAM 3500 Megacab, 5. 9L, 135,000mi.

 

[AH64ID]

Have you updated your software at all?

I want to say that was an issue when the ECM saw a big difference in the coolant and battery temps at startup, and was fixed with a ECM software update.

 

[dmlappert]

Bought used last year. I'll check on updating the ECM software. Thanks.

 

[TLane]

How cold is it that you're using the block heater? The user manual on my 2008 indicates to only use it below 0*F. The ECM does a sanity check of the temperature sensors (engine coolant, incoming air, etc. ). If the engine has been off for several hours then the temperature sensors should read the same (within reason). If they don't agree with each other, it will set a code. If the temperature is below something like 20*, then the check is not performed. Running the block heater above that temperature may cause the ECM to think that the sensors are bad.

 

[AH64ID]

I can use my block heater on 40° nights and not set a code.

The owners manual doesn't say not to use it above 0°, it says it's recommended or required below 0° and required below -20°.

Block Heater Usage
A. Temperatures below 0°F (-18°C)
• Block Heater Required for 15W-40
• Block Heater Recommended for 5W-40
B. Temperatures below - 20°F (-29°C)
• Block Heater Required for 5W-40

That excerpt is the same from an 06 and an 08.

 

[rbattelle]

The battery temperature sensors are watching for a change in battery temperature over time, rather than an initial temperature. There are lots of cases of false errors with these, but this is the first I've heard of a repeatable failure linked to the block heater.

Just as an experiment, can you park the truck facing the opposite direction one night and plug in and see if you still get the code? Sounds silly, I know, but wind direction can play into the issue.

Any chance the batteries are going bad? That's what the sensors are meant to detect. Maybe they're working.

-Ryan

 

[Bob4x4]

There was a flash for temp rationality years ago... ... ..... but for those that avoid dealers you wouldn't have had it. If you were to use a smarty that has updated software you would have it.

 

[steved]

Since you've narrowed it to the block heater, you wouldn't think the block heater is shorted/compromised and that could be causing voltage to be applied to things in the truck...



I'm thinking about a first gen that used to bite me every time I grabbed the door handle... it was a bad element, and would still heat and would not trip a breaker. But it would shock you every time you grabbed a door handle (which was chrome plated cast metal, not plastic).

 

[Bill Stockard]

Since you've narrowed it to the block heater, you wouldn't think the block heater is shorted/compromised and that could be causing voltage to be applied to things in the truck...



I'm thinking about a first gen that used to bite me every time I grabbed the door handle... it was a bad element, and would still heat and would not trip a breaker. But it would shock you every time you grabbed a door handle (which was chrome plated cast metal, not plastic).

That's why you should use a 3-wire extension cord and plug it into a GFI outlet. It could kill you!



Bill

 

[steved]

That's why you should use a 3-wire extension cord and plug it into a GFI outlet. It could kill you!



Bill

In 1991, when did you see a garage with a GFI? They were hardly used at that point... and I bet 90% of the owners on this forum don't plug their truck into a GFI protected outlet.

 

[Deleted member 995608]

My 04. 5 throws the same code. I just ignore it and it goes away by itself after a few starts.

 

[AH64ID]

and I bet 90% of the owners on this forum don't plug their truck into a GFI protected outlet.

I purposely don't, GFI's don't like heat elements.

 

[bheiting]

Does the truck have battery warmers installed as part of the OEM winter front kit? May be a malfunctioning heating element or short. Cummins has a free tech line listed on their web site.

 

[Prairie Dog]

In 1991, when did you see a garage with a GFI? They were hardly used at that point... and I bet 90% of the owners on this forum don't plug their truck into a GFI protected outlet.

NEC required them in garages beginning in 1978 I believe and outdoor receptacles a few years before that.

 

[dmlappert]

Thanks all for the responses... . Reflashed and the error code no longer occurs... . I'll be keeping by the below 0 recommendation.

 

[AH64ID]

Thanks all for the responses... . Reflashed and the error code no longer occurs... . I'll be keeping by the below 0 recommendation.

Good deal.



The below 0° is a recommendation based on starting ability only, and has nothing do with engine heat and warmup. Many people use the block heater above 0° for a faster warmup, which is better on the motor than cold idling.

 

[George Cameron]

It's nice to have heat in the cab quickly on cold mornings