krwyellowZ28

iTrader: (10)

I used a 1998 LS1 temp sensor to LS swap my '70 GTO and try to retain the original ECT gage. I was hoping it'd be as simple as hook it up and go, but I didn't get that lucky and the gage pegs out as soon as the key is on.

Has anyone measured the resistance of the sensor sitting in boiling water? I'm assuming I can just dial down the signal with an in-line resistor to coordinate with my stock ECT sensor and therefore read close on the gage. How have others made this work in their swaps?

Thanks for the help,

Kyle

garys 68

iTrader: (1)

post 5
https://ls1tech.com/forums/conversio...auge-59-a.html

bczee

iTrader: (12)

What I did was just use the Passenger side head and mounted the old OEM Car sender there.. is there a reason you can't use that location ? Left the standard sender for the PCM to use.
If you could, that would eliminate the guess work out of getting the right resistance and I wold guess that the gauge would be off some and during the full sweep of the gauge during the change in range of temp.

krwyellowZ28

iTrader: (10)

THANK YOU!! That is exactly the info I was looking for. I'll still boil my original sensor just to verify the gage in my car, but you just saved me a lot of time and spilled coolant!

I had considered doing that, but I wanted to clean up as much wiring as I could, so I put the 1998 sensor in the passenger head, and plugged the driver side head. Everything is all wired up for the gage to work, now I just need to get the resistance correct.

rosco11

There is an easier way. First, if your gauge pegged to hot, it is grounded. That is another issue.
If you want to use a stock gauge with a LS swap, there are 2 ways,
1 - bolt on a factory sender for your car to the engine with an adapter. It will be close but will not read correctly because of the adapter.
2. use a 98 LS sender, 3 wire, and run the green wire to your oem gauge. You will have to change the resister on the back of the gauge.

BTW, for my 69 pontiac it was a 150ohm 1/2 w resister to answer the dozens of posts on the subject that talked a lot but never answered the question.

to find what you need, buy a pentameter on amazon for about 10 bucks, remove the oem resistor and wire that puppy in. Get your engine to operating temperature and turn the dial to the point where you get the gauge to read what you want at operating temp. Then measure the resistance on the pentameter. Buy a resister. like 6 bucks for 20 or more. Will also NOT BE accurate at any other temperature than where you set it to read at operating temp. It will not scale properly. However, it will be exact where you set it and that is enough to see if it is running too hot or not, even if beyond that point it can be off by 10 or 20 degrees.

On my 69 GTO, it only had hash marks to begin with. i set mine to the middle at operating temp. If it moves towards the 3/4 mark, i know i have a problem. So working as intended.