i ride dangerous have you ever handled live spark cables I have... I was testing spark plugs and coils if you get a shock that means it's working lol

 

So today was a very interesting day with my truck. For about 2 weeks the fan for the hybrid battery was working just fine. Today was a rather nice mid to upper 80 degree afternoon today when I went out to the stores. The first part of my drive was good, I drove a few miles and made a couple of stops where the truck was turned off in between stops for 20-30 minutes per stop. After my 2nd stop suddenly the check engine light came back on and I immediately knew what that meant and the app on my phone confirmed it. I finished my last 2 stops with the check engine light on figuring I had only a few miles to go to get back home. What I didn't understand is the crazy temp readings the app was telling me. It was under 90 outside and I had the windows closed and the AC on and the batteries were reading 130ish degrees and the inlet and outlet air temps were way off. No way can you be taking in 100+ degree air when the cabin has the AC on at 66 degrees and it was chilly in the truck. Maybe because the fan wasn't blowing the inlet air temp readings were thrown off. When I got home I took the plastic hybrid battery cover off and used my laser thermometer to check the temps of the battery case they were barely over 100 degrees so if the batteries were really at 130+ degrees how is it the metal cover was barely hot to the touch and reading just about 100 degrees?

So I pulled out my Tech2Win PC and got to where you can play with the hybrid fan to test it by adding a percentage increase of power to the fan. The fan was showing zero RPM's and I could not speed the fan up by using too no matter how much power I tried to add. So I got brave and I disconnected all of the 12 volt and 300 volt power cables and pulled metal battery cover off. I wanted to see the fan and if the connections to the fan were good or not. I also looked at all of the relays in the fuse box in case one of them was a relay for the hybrid fan. I made sure they were all seated good while the power was off to the truck. The connections to the fan looked good but I was not sure how to test the fan other than using the Tech2Win PC. After about an hour I gave up my internet searches on how to try and test the fan by itself. I decided to try and do something even more stupid and "ride dangerously" as some would say. I hooked all of the power back up put the safety switches back in and started the truck. Now I was able to visually see if the fan would spin or not with the cover off. There was no fan movement even knowing the battery temps were calling for it. I tried again for 30 minutes or more to see if I could manually increase fan speed but it was not responding to the request. I was basically giving up hope for this fan module. I figured it finally had died. While the truck was running this entire time I went to the front of my truck to go back on the PC to do some additional internet searches and suddenly I hear this loud noise coming from the back of the truck. The fan on it's own decided to work again and it came on at high RPM all on it's own. Why all of a sudden is the fan working now? Nothing else I touched did anything to make it work for hours and now all of a sudden it starts working again????? Without pulling the battery from the truck it's hard to see where exactly that fan control wire goes. I'm assuming it combines with more wires as it gets closer to the battery control module because the 4 wires going to the fan do not appear at that control module itself.

Is there a relay for the fan hidden in the battery pack that is possibly faulty? Is the battery control module or some other component the root cause of the problem since the fan works when it finally gets power? I'm not sure where that connection from the fan goes so I cannot tell what could be faulty in-between the fan itself and the battery control module.

I'm gonna talk to the guy at Best Hybrid Batteries and let him know what I found (not necessarily exactly how I found out about all of this today) and make him figure this out once in for all. I cannot keep roasting these batteries because the fan all of a sudden stops working.

 

Yes, there is a relay for the fan inside the battery case. It is controlled by the battery control module (BECM) through the white wire with green stripe. From the relay, two terminals (2 and 3) both connect to the external connector on the Red wire with white stripe. From here it goes to 12V through the BECM FAN Fuse (15A) in the Aux Fuse Block. When the BECM commands the fan relay to turn on, it grounds the white/green wire connected to Terminal 1 of the relay. Power from the relay is provided to the fan through the pink/dark blue wire on Terminal 4 of the relay.

 

sent you a message in another thread about disabling auto stop.. Any chance you could give me more detail in that thread? Thank you

 

Shift it to M4 then it's disabled.(pull the shiftier all the way down ). it also disables AFM or v4...

 

Gotcha that's what I do when I'm about to stop. Didn't know that would cut the AFM as well.. I had it deleted through computer. Thanks for the help though I'm sure I'll be asking more questions.

 

So I finally had the relay replaced in my battery pack last week by shop who replaced my battery pack. Unfortunately the old relay tested good but he replaced it anyway. I didn't get off of the shop lot and the check engine light was back on for the same issue. No hybrid battery pack fan movement.

He did say hes willing to replace the entire battery pack with another one because he has replaced everything within the battery pack that is related to the fan. He replaced the fan, fan relay and the module in the battery pack that controls the fan.

When he first replaced the battery pack the fan was working without any issues for months until the problem occurred. Since then it was intermittent and more recently it will not come on at all no matter what you try and do.

I do find it interesting that when I look at the two codes the P0A81 code for the fan 1 control open circuit is coming from the Transmission control unit. Why wouldn't that error code come from the Hybrid powertrain control module like the P0AC4 error code? The P0AC4 error code is for the Hybrid powertrain control module requesting the MIL to be activated which makes sense because it controls that fan unit. But why does the transmission control unit know anything about the status of the hybrid battery pack fan?

Do you think replacing the battery pack make any difference?

If a new battery pack does the same thing is there anything else that can be causing this issue to happen?

I can't imagine there is something outside of the battery pack that could be causing this issue but maybe there is something I don't know about.

 

this tahoe has a High Speed Canbus so everything can interact with each other...

 

Some people say that all this technology that has developed since around 1940 was reverse engineered from alien spacecraft at Area51 and we still have some mysteries that cannot be solved.
LOL just messin wit U could not help it we watched Nicolas Cages crazy movie "Color Out of Space" last night.
Yes have the Hybrid battery swapped out for a known good one, they have something messed up on this one. Could be as simple as a temp sensor gone bad or a chaffed pinched wire. Not worth the trouble and effort to try to reverse engineer the thing, just swap out the entire battery and then you can drive out to visit Area51 without a check engine light on at all..........

 

Hopefully the battery replacement fixes it. I'm tired of running around with my frankenfan setup.

Don't laugh it works.I keep an eye on the battery temps with my CarScanner app and I keep them from overheating on the warmer days.


Lasko X-Blower Utility Blower Fan and 3 inch flex tubing.

Blowing cool cabin air directly into the air intake port.