@1FastBrick Do you know when the low coolant sensor on the reservoir fill tank was removed? I was going crazy trying to find it on this truck. 🧐 The tank just has a little solid nipple down there but no sensor. How does the ECU know it's low on coolant? 🤔

I'm pretty sure my 99 has it. The harness leg going to the MAF has the connector for the low coolant sensor IIRC.

 

I know everything about nothing!

On the 00 2500 I just did with a 99 production date, it had a sensor but the wiring has a break in it somewhere so it thinks the coolant is low. My my 06 Gmc Spring Special does not have one in the tank. You are correct about the location of the sensor wiring as well.

I would have to look at some schematics to see when it may have been omitted.

 

Interesante...

Here's the cooling system from AllData for my 2004 suburban. It does show a coolant level switch. I'll have to check it out when I get home today.

I'm trying to remember in my 06: a while back I had those coolant tees near the firewall break and I limped home stopping at every gas station to buy water. I don't recall ever getting a low coolant message, but maybe a over temp message? I honestly can't recall...


BTW, it looks like normally open switch, so if the wiring had an open somewhere it would never read as low coolant even if did, right?

Along those lines, my 1999 has a "check windshield washer" on the message center every time I fire it up, only when I fill the reservoir. I think a long time I removed that switch and maybe installed it backwards? Or it's just bad? Ah dang, another thing to add to the to-do list, LOL 🤣

 

Maybe an overtemp when they decided to delete the coolant level sensor.

The washer one is common. Usually the stupid pump starts corroding and then leaks. Or the sensor gets corroded Usually from a leaky battery. Some times road debris takes out a wire too...

 

@1FastBrick I first get P59. Then do E38. See

 

Ok, so the 2004 does have it but not the 2006. I didn't bother on the 99 Silverado but I know that one also has it.

 

Got the harness back on the engine. Gave it a quick clean while it was off.

 

I found a ground wire had some chaffing. And speed sensor connector pigtail I bought last time I couldn't find in my garage mess, so I used liquid electrical tape. The wires were cracked a little further back.bHopefully that will work. 🤞

Then on the way to work my money light came on. It was a lean code both banks, with improved fuel trims as I increased the rpm when I got home and checked. Classical vacuum leak symptoms and I recall hearing one the night before. I had an extra hose for the pcv valve, which was leaking at the pcv boot.

All good now.

 

Umm. I'm pretty sure my engine has slowly developed an intermittent lifter issue. It idles kinda rough and it's running lean. Sometimes I get a tick driving on the highway but it goes away.

Today it did it when I got home from work. Sounds like it's coming from the top, near the valve covers. Fuel trims were like 25 and 19 percent. I was initially thinking my lean condition were my O2 sensors and I've actually bought 4 new ones, but I'm convinced mine are still good. Oil pressure is still good. No knocking when the tick is not on.

Am I correct that the hydraulic lifter not pushing the push rods to the correct height will cause a lean condition because the valves are not opening all the way? How can you know if it's the intake or exhaust valve? Not that it really matters.

Would it be worth replacing cam, lifters and pushrods on it? Or might as well pull the engine to do a complete overhaul? Probably need to do it over the holiday break because it's the daily for school kid dropoff.

 

A valve sticking open would cause a lean condition. Not opening all the way would only be like a lower lift, shorter duration cam.