according to the wire schematic i looked at there should be black/white wire and a orange wire. The orange wire is on pin A8 of the ECM and the black/white is on pin A9. what voltages should these have? I can't get a scanner to read my computer but the check engine light works. Any help is much appreciated thanks

 

A8 is serial data.

You can throw a scope on it to see if it’s putting out.

A9 is the test terminal, probably has 5 volts.

When you say “the check engine light works” do you mean you can get code 12 to flash when you use the ‘paper clip method’?


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what is serial data and what do you mean by a scope and putting out? Yes the paperclip method works for the check engine code but it is also throwing a 15.

 

Serial data is the bitstream present on that line.

If you had an oscilloscope you could look at the data in real time.
Don’t worry about not having one for this repair.

Code 15 indicates there is a problem with the coolant temperature sensor or wiring going to it.

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i am trying to hook up tunerpro to my car. but it doesn't seem to be working. Once i get tunerpro up and running i can see what the cts is doing. I have already replaced the cts and checked the wires but can't seem to fix the code.

 

To clear codes without the TunerPro, pull the ECM fuse for about a minute.

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Happy Racing!

 

yeah i know how to clear the codes thats not what i am trying to figure out.

 

this might be a stupid question, but did you clear the code after replacing the CTS? and then the code popped up again,


answering that questions will help people anwser you

you replaced the CTS and checked the wire, only other answer i could think of is somethings up with the ECM itself or the CTS you replaced was a bad unit

my cars ECM went bad and it was throwing a couple different codes i could not get rid of until i changed the ECM, havent had a problem since

 

the computer was replaced shortly before the CTS code started coming up. I clear the codes by disconnecting the neg. terminal on battery for like 5 min. start the car up and within a couple min the SES light is on. Also throwing a code 22, not sure if i mentioned that earlier. The TPS and CTS share a common ground. however the TPS code has been there since i bought the car and have never figured out the problem replaced about everything. but this is the first time the CTS code has come up in 6 years. I checked all the ground on those sensors and they seem fine. Thanks for the help.

 

that Code 15 you have has me stumped, because there are only three possible culprits

ECM
CTS
or wiring from ECM to CTS

and as long as you get the 5V ref signal from the ECM to the CTS and the ground is good then your wiring and ECM are both good, and would lead to a defective(even if new) CTS

if its not that then it has me stumped as i have always thought it could only be those three things

 

yes that is my problem, all three culprits have been checked ECM and CTSare new and no solution has been found. I could always buy another CTS but i'm not a big fan of just replacing parts on a whim. I have wasted too much money that way in the past. Even if a CTS is only like 15 dollars.

 

The ground for both the TPS and CTS is at the ECM... Check to see if the terminals have come out of the ECM connector. I had a primary ECM ground do that once. However, if you had a problem with the ground on both, your MAP and IAT wouldn't be working either, because the TPS and IAT share a ground and the CTS and MAP share another.

:edit: And all you have to do is check the resistance on the CTS.

 

Could be a broken wire in the circuit

Do a continuity check on both the ECM side and ground side. Thats free

Anything over 1ohm is a problem

 

I am confused on how to do a resistance check on the CTS. I was explained how once but didn't make sense. anyone help. Thanks so far..

 

Use a multimeter across both pins with the CTS at various temps and record the resistance

Compare to a known resistance value chart for the specific CTS. It should be close or way off

 

And it shouldn't either have no resistance (shorted) or infinitely high resistance (open). Basically, any reading is a good reading for starters.

 

the guage was not register temp yet so it was below 100. but i got a resistance of 1.6 Kohms.

 

after coming up to 140 it is reading 0.64K ohms.

 

at 160* it is reading .46 Kohms

 

so i found a loose pin on the connector. everything OK now. thanks guys.

 

good to hear that......aint this site great

 

 

haha and i was just about to tell you to check the pins, i was reading on another thread where a member had a Cooling fan issue and it turned out to be a loose pin and nothing else was wrong

 

yup thats all it was. Well at least for that problem. The thread started out trying to figure out why my ALDL cable isn't working. I have tried it with Tunerpro and WinALDL and it doesn't seem to work. lets see if you guys can help me figure this one out thanks.

 

Now that i have never messed with, because i have not made a cable even though i want to

is yours a home made cable or bought?

and while i am here, do you or any of the other experienced WinALDL users know where a good pinout/instruction guide is for making a cable? i would really like to run winALDL with my car

 

i bought my cable from ALDLcables.com, having issues getting it to work though.

 

Check to see what terminal of the ALDL the serial data wire is on. It's orange. It'll either be in pin E (IIRC) or pin M. If it's in pin E, try moving it to pin M, under the black/white ground wire. Some cables, I've noticed, don't like pin E. Also check your ECM connection as stated above. If that doesn't work, you might want to see about another ECM.

 

the ecm is a new AC delco

 

well a loose pin was your last problem, maybe a pin is loose at the ALDL connector or at the ecm, now you just need the pin locations on the ECM, in which i have the ECM schematic, so let me see where they are

 

hahaha, correction you know where those are as i just reread your first post, lol, but did you check to see if they were loose there or at the actual ALDL connector?

just a thought

 

well no they were not loose but the pins on the CTS were not actually loose. the female end was simply bent out of the way. a friend pointed it out to me. I never would have looked and that connection and said it didn't look right however it fixed the problem by using a pick to bend the tab back out a little.