peterz123

Hi all hope someone can steer me in the right direction. On some cold mornings 30 F or so,
I get what appears to be an ECU B fuse issue- No nav, all the dash warning lights etc, fairly common for the ECU from my readings
I've changed out the fuse several times, pulled the battery terminals to reset the ECU, have functional mirrors etc. Once the weather warms
up the problem goes away. Are there any relays other fuses or other electrical components which might be affected by the cold in this
system/loop. I can't get the car out of park to drive it until it warms up. Battery seems fine and cranks the car over easily, central locking also works.
Some cold days it's fine.. I'm a fairly experienced mechanic but I'm remote for work and have limited tools and no shop manual for this otherwise superbly reliable
truck.

thanks

DiabloX22

Electricity ALWAYS takes the easiest path. When it's that cold metals, materials contract, so I would look at the main fuses to see if they are all getting power with a meter, if you dont have 1 get 1 only about 15 bucks. If they are I would check connections and grounds to the box. I usually pull up the diagrams before I answer to help explain things, but can't now. Any questions or anything just reply or msg me

peterz123

Thanks - It's been driving fine but the weather warmed up ...it dropped down again last night and the problem reappeared. I did get a multimeter as I now have a charge/battery warning light- I suspect the battery is getting tired, cold weather overnight and it drops below the voltage needed for the systems in the car. With the car running I see 13.85, at idle it drops to 13.58 or so with lights on ac and set heaters so the alternator while not at the top of the range is ok I'd guess but I did not do an average test. By the time I'd cranked the car over again the batter was at a healthy 13.2 with the engine off and everything was working again. I don't have a load tester but with another cold night I'll check the battery in the AM before starting the car and see what I've got, if it drops down to less than 11 or so I'd guess the battery is bad - I don't have an age on it it's an interstate battery with the old style cells and acid service - thanks **** Edit- Alternator is fine output is 14.3 V- I had replaced the 7.5 a alternator fuse in the wrong location during troubleshooting and caused more issues, bat/charge light is now off. Took the car to AutoZone and did a load test as I suspected the battery was bad going to replace the battery and see if the issue comes up on the next cold day

DiabloX22

Hope that fixes it. Let us know either way!

2013FSport

iTrader: (2)

There has been a flurry of IS no starts with various ailments. 4 tie back to bad connections at the ECM. In short, w battery disconnected, remove the ECM and specifically look for screw lugs that are loose, discoloration, growth, burning etc of all mating pins.

It never hurts to apply dielectric grease either if there is any doubt about moisture getting in.

Of course another approach is to take a hair dryer and heat ONE item only, give it time and test it. If heat is the issue (lack of in this case) and you isolate it, this could be a huge leap forward.

Another option is 25 watt protected bulb laying near suspect area over night. Try not to burn anything.

Good luck.

peterz123

It was cold out last night so of course this morning the GX did the same old thing- Put the key in, no steering wheel, all the dash lights no nav clock etc. I'm going to get a bosh replacement battery today as the Costco interstate has a dead cell. Interestingly I pulled the 10a air suspension fuse and put it back in and everything miraculously works. I'm posting mainly to get more data for future electronic issue troubleshooting for other forum members, the air suspension is working fine no errors and goes up and down and levels perfectly.. once the car is going. My question is does anyone familiar with the circuit know if the Air Suspension initializes at startup with the key in? I suspect that the current draw is insufficient based on the bad battery, but it did seem curious...