Loss of all needle gauges, ABS light, smell of coolant, no codes

Experienced a weird one last night, wanted to run it across the forum to see if any of you guys had experienced anything like this.

Last night, I started the Tahoe and immediately noticed the ABS light was on and none of my needle gauges worked in the cluster, except for the voltmeter. All of the cluster lighting worked, however. The DIC was displayed dashes in place of number values for the ambient temperature, etc, as if it wasn't communicating.

I drove home without a hiccup until I got about 10 miles up the highway (I was a mile from home at that point). I stopped at the store and threw in my OBD2 tester, and found no codes present. At the same time, while I was key on/engine off, the gauges started working. I started the truck and found the truck was overheating (normal is straight up at 210 degrees, I was about 230 which is about 2/3 of the way up). I drove home and it cooled back down to normal, then started to creep up again as I was turning in my driveway. I did smell coolant, but didn't really see any evidence of a leak. It was tough to determine though, since it has been raining all week. I did notice the fan was operating.

This morning I got in the truck to head to work, all gauges are working fine. It was in the upper 30's outside, so I turned the heat on and headed off. Usually the ~1 mile drive to the interstate is enough to get some heat, but it was stone cold. The temp was a full 210 degrees by then, like normal. I hopped on the interstate for the 10 mile highway ride to work, and found the temp crept up to 230-235ish and didn't venture any higher. If it went up further I was going to pull over, but it sometimes crept back to the normal side and never went over 230 or so. I cut the AC on to pull the fans on, but it didn't make a difference with the engine temp. Even with the AC on, I did notice some heat from the vents....which was weird and short lived.

Going to take a work truck home tonight and leave my 'Hoe here until I figure out a game plan. Wanted to see if anyone had any experiences similar to give me some direction on what to look for. FWIW, 2010 PPV Tahoe 2WD, MFI.

first thing I would check is your battery cables, pull them off and clean them up and put them back on nice and tight even they look ok and check the ground cable over real well the ground cables are a known issue to just go bad from the inside out (corrosion).
even if the instrument cluster had gone completely wacko it would not cause any mechanical problem because you can pull the cluster out and drive all day long and it would affect nothing but would eventually throw a dtc saying it couldn't communicate with the cluster.
so your heating issue is a separate problem if your smelling coolant then only two things are possible.
1. you have a leak
2. it has overheated and spit some out the reservoir overflow
your description sounds like maybe a water pump or thermostat issue either way I would get directly under the truck with a flashlight and take a good look, fluids like to flow down so look directly under the radiator/hoses, water pump, and along the firewall on the passenger side where the heater hoses connect and basically inspect all of the hoses on the passenger side.
also from above with the hood open look straight down on the left and right sides of the radiator sometimes the plastic sides will get a small crack. the coolant reservoir tanks can crack and leak also.

abs light is also a separate issue, but after checking your cables and cleaning them up I would wait and see if it comes back on before digging into that, even if the abs light is on and/or has a issue your brakes will still just like intended just the abs may not kick in if you had a emergency stop so your wheels would just lock up instead of pulsing the pads.

RichardCranium said:

Experienced a weird one last night...

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I think you have two separate issues the one being you're low on coolant for some reason. Those chintsy code readers cannot read BCM codes, that's where the dash light information will reside.

Step one... top off your coolant... that is why it's reading higher than normal and you have no heat... because there is insufficient coolant in the system to cool the engine or heat the cabin.

Step two... figure out where your coolant is being lost. The plastic quick disconnect T- fittings where the heater hoses meet the front heater core at the firewall are notorious for getting brittle and cracking/breaking/leaking.

This is definitely all related.

I've found the possible culprit, will confirm on Monday. The truck has been sitting for 2-3 days now, I started it up and moved it to a different location today for the weekend. It never overheated today, but also note I never saw any evidence of a coolant leak prior as well. When I moved the truck, I drove 1.2 miles in 43 degree weather. By the time I reached my destination I reached full operating temperature, but still had no heat.

I let it idle for 5 minutes in the parking lot, noticed a small leak that was coming from the vicinity of the radiator. I shut the truck off, and immediately noticed coolant dumping from the weep hole of the condenser box (where the AC drains). I'm assuming I had a clog in the heater core, and it over-pressurized and burst in a few places. Also the ECM is under the hood, I'm wondering if it got sprayed directly causing the weird and temporary electric issue with the cluster and ABS lights.

I'll tear the radiator and dash out hopefully Monday, and figure out what all needs replacing.

RichardCranium said:

This is definitely all related.

I've found the possible culprit, will confirm on Monday. The truck has been sitting for 2-3 days now, I started it up and moved it to a different location today for the weekend. It never overheated today, but also note I never saw any evidence of a coolant leak prior as well. When I moved the truck, I drove 1.2 miles in 43 degree weather. By the time I reached my destination I reached full operating temperature, but still had no heat.

I let it idle for 5 minutes in the parking lot, noticed a small leak that was coming from the vicinity of the radiator. I shut the truck off, and immediately noticed coolant dumping from the weep hole of the condenser box (where the AC drains). I'm assuming I had a clog in the heater core, and it over-pressurized and burst in a few places. Also the ECM is under the hood, I'm wondering if it got sprayed directly causing the weird and temporary electric issue with the cluster and ABS lights.

I'll tear the radiator and dash out hopefully Monday, and figure out what all needs replacing.

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no, highly doubtful if the heater core burst you would have coolant inside in the passenger floor area and it would not have made it into engine compartment at all.
it is more likely one of the heater hose connectors at the firewall entrance has cracked and it is running down the firewall and appearing to come from where the ac condenser drips.
even still pretty unlikely anything would have affected the ECM

Might well be right, all I can see right now is from up top. It'll go on the lift in couple of days and hopefully it'll be a bit more clear.

The bottom of the fan shroud and radiator is always moist from the leaking trans cooler lines (typical seep from the factory compression couplings), so the drips from the front could be running down from those heater core lines from the firewall.

I did forget to mention my upper radiator hose was hot at the rad, and the lower hose was ice cold. I'm still thinking I have a clog. Hopefully I'll find out Monday.

Doubeleive said:

it is more likely one of the heater hose connectors at the firewall entrance has cracked and it is running down the firewall and appearing to come from where the ac condenser drips

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One of those cracked for sure. Kind of weird, otw to the shop where the lift is the heat worked fine. It was still running 220-230 though. Looks like a clog in the radiator, it isn't flowing like it should. Replacing the rad and repairing the heater hose connection and hope to be solid again. Waiting on a friend to bring a scan tool over to read the ECM and BCM for any codes for the cluster.