Low Coolant Light will not go off

[89-W-Body-Regal]

I had my 2.8 V-6 replaced with a reman jaspers motor last month in my Buick Regal due to water mixing in the oil. The cylinder walls had scoring and the ecm had water in it. We put about 150 miles on the new motor so far.
 

The shop that put my reman engine in for me told me they couldn’t get the low coolant light to go off. I had them replace my coolant level sensor.  They also told me the ecm was full of water so they replaced that with the part I provided. The part number of the ecm I found myself was when GM still reman them back then in house. This unit was an NOS I found off eBay. The shop thought maybe the ecm wasn’t correct for my vehicles options. They said it does fit my application but it could be this ecm was an optional ecm which would be optional on these models back then. Mine being a base model, they think this was the higher end ECM and mine was different. But they said everything seems to be working fine with that ECM. It’s just the low coolant light that is staying on. I don’t think the ecm has anything to do with the low coolant light does it? I know clearing codes and having them come back would indicate a bad ecm. But I don’t think a low coolant light would be related. The shop says just drive it and see how it drives with the new engine in it. Bring it back in a couple of weeks and we can check that light out.

The part number of the ECM I got will be shown in the photo. My original ecm from the factory was replaced in 2007 with a cardone industries one that was complete shit. I wanted one from back then when GM done their own reman. So I got an nos one that the dealers supplied when the cars were still new. The GM parts catalog says the part number for the original ecm that came from the factory is 1227727 and that part number was interchangeable with the part number you see in the photo which fits my application.

Coolant is full and stays full. I didn’t check the coolant level sensor to see if it could be a bad part out of the box. It’s a nos part I got from a dealership. You can’t find coolant level sensors new by Acdelco anymore. So I found the last one and had the shop replace it. They are super expensive to replace. But I was able to get one for a good deal from a Chevy dealer in Nebraska. 
 

Do you think it could be a wiring issue with the cluster? I don’t know what the shop was talking about when they said, they think it’s an aftermarket ecm and that’s why coolant light will not go off. This isn’t an aftermarket ecm. It’s a genuine GM part by acdelco. This is before they out sourced their parts over seas and done all the programming and remans their self. If you’re still able to come across one reman within GM I would get it asap.

 

Let me know what I should do, should I inspect the coolant level sensor to make sure it’s working?

 

 

PS. I had a similar problem like this a couple years ago. I replaced my intake gaskets and the low coolant light would come on after refilling the coolant. I replaced the level sensor and never came back on.

Edited December 4, 2023 by 89-W-Body-Regal

[White93z34]

As I recall... the ECM has nothing to do with the coolant light on the dashboard, at least I'm 90% on that

That said, water in the ECM is not good for sure replace that.

From what I can see the 16198260 is a direct replacement for the 1227727. Just make sure to change over your Memcal (chip, PROM whatever you wanna call it) so the computer has the right calibration.

The coolant level sensor is on the radiator, passenger side near the top, make sure the connector is free of corrosion. 

I forget if the early cars have a 2 or 3 wire coolant level sensor, check yours out, if its a 2 wire just try jumping the terminals together and see how the light responds.

that said a quick search on RockAuto shows one for a 89 2.8 regal for $20 (GPD #1712534)

[89-W-Body-Regal]

DCan I use this to check the wire at the coolant level sensor? If the bulb lights I assume I don’t have a short at the connector and it’s just the sensor? 
 

https://www.jarheaddiag.com/shop/p/jarhead-diagnostic-load-test-light

 

someone also told me to, have key on engine off,  disconnect coolant level sensor, if light on cluster goes out the sensor is good, if light doesn’t go out the sensor is bad. They said if no change in light, use a paper clip to short the sensor wire to engine block. The light should then change. I have no idea how to short the sensor wire to engine block. So I thought the load test light would be good for checking a short

Edited December 5, 2023 by 89-W-Body-Regal

[White93z34]

just short the 2 pins together with a paperclip or something, I forget if its supposed to be normally open or closed but try different things and see how it responds don't make it more complex then it needs to be get the basics out of the way first.

I'd have to consult the service manual to see how its supposed to behave