2000z28err

anyway to test the relays bye swapping the to different sockets.. theres 3 relays

Injuneer

The three relays are interchangeable. What specific problem are you trying to solve? The PCM will sets codes for problems on the control circuit side of the relays.

2000z28err

the problem is the cooling fans dont come on. they only come on if i put the a/c on. i swapped fuses but i dont know if it did anything. when do the cooling fans come on? what temp?

Injuneer

Not sure of the exact temps in the 2000, but earlier models were low speed at 226*F, high speed at 235*F.

The fact that the fans come on with the A/C confirms that the relays are working fine, the fuses are OK, and that the PCM can communicate with the relays. If your coolant temp is above 235*F and the fans aren't on, it could be a problem with the coolant temp sensor that connects to the PCM.

2000z28err

im going to purchase a co0lant temp sens. but my temp gauge is working inside the car? doesnt the coolant temp sens control that too ?

Injuneer

I'd use a scanner or scanning software to determine what coolant temp the PCM is reading, before buying a coolant temp sensor. There would be codes for a shorted or open sensor circuit. But no code for a problem with the sensor accuracy. The scanner may also be able to tell you if the PCM is commanding low or high fan levels.

From what I've read of the coolant temp dash gauge in the LS1 cars, the gauge just goes to the middle and stays there, and is not an accurate indicator of temp, unless the engine is extremely hot or extremely cold.

The 2000 manual does not indicate the number of coolant temp sensors. Again, earlier cars had one sensor on a 12V circuit for the gauge, and another on a 5V circuit from the PCM. Some used 3-wire sensors, which actually had 2 sensing elements in one body. I just don't know the details of the 2000. The dash cluster has it's own "solid state logic" module, that carries Class 2 data with a feed from the PCM. Whether that allows the single coolant temp sensor to feed the PCM and then the PCM feeds the dash cluster is not clear to me.

2000z28err

yea that would probably be a better idea. idoes advanced auto or autozone have the scanner?

GaryDoug

Like Fred said is how it works, starting in 99 there is just the one sensor body with just one element. The 98 had two elements in one sensor body. The PCM sends the coolant temp data to the instrument panel controller.

I am not sure a parts store will have anything except a trouble code reader for customer use. If they have one for real time data, you might ask for a "demo". Otherwise you can buy an ELM327 cable for the pc and use the software that comes with it. The Chinese (blue/orange) knockoffs are cheaper at about $15 but the software is more difficult to install and use. The ELMscan5 (blue/red/white) is the best at $25 and has decent software. If you want to use your Android phone instead, you can buy one of the Chinese-made Bluetooth ELM327 adapters and download the Torque Free app. It will read the engine temp as well.

2000z28err

the bluetooth one looks cheap enough.. ok i see. that will tell me the problem? awesome

GaryDoug

Into the 16-pin connector under and to the right of the steering column. It will not necessarily tell you the problem, but it will tell you the sensor reading.

2000z28err

i was looking at the item is the autel ms300 the same product

GaryDoug

No, that is a handheld code reader only. But it is a good one for the price.

2000z28err

im going to order the elm327 give that a shot. stop bye advanced tomm see if they have a demo. gonna go for a long ride till temp hits over 210 to see if fans do come on . thank u guys for the help. u know the feeling when your f-body having issues. theres no other care in the world.. lol

2000z28err

ok, yesterday i swapped 2 relays #12177236. so today i went for a highway ride till the temp gauge hit 210 pulled over and the fans kicked in little after 210. now is that normal? most likely its 1 of the fuses cause it was almost overheating the day before

Injuneer

Every 4th Gen I have ever seen turns on the low speed fans (or fan #1) at 226*F and high speed (or fan #2) at 235*F. The engine is designed to run at 210*F, yielding the best balance of reduced emissions, and decent fuel mileage. 210*F is not too hot. Maybe there's something "odd" about the 2000 models that I am not aware of.