CTS problem

KING_3 · Post by **KING_3** » Tue Jun 03, 2008 4:51 am

Hey guys
I just had my ECM scanned (due to problems i think is being caused by my coolant temp sensor)
and guess what, the scanner was reading 150degC and my coolant should be boiling by then, but it is not.
Because of this my ECM is thinking that the engine is in overheat, causing my idle to adjust accordingly and my A/C to be shut down.

Hope you can help me where to look at, or what to check first
- I've already tried replacing the sensor itself - same results
- Also tried laying out new wiring from the ECM to the sensor (positive only since the ground wire is being shared with the TPS) - still the same

- Also tried putting a voltmeter on the ECM terminals for the CTS and i'm reading low voltage (less than 1volt), which agrees with what i got from the scanner
- I will try next to connect another ECM, but i'm still trying to find one

Any more suggestions?

Many thanks!

MMamdouh · Post by **MMamdouh** » Tue Jun 03, 2008 7:14 am

are you sure you are checking the temp sensor for the ECU not the one for the temp gauge??

MMamdouh

Daniel · Post by **Daniel** » Tue Jun 03, 2008 11:57 am

+1

The CTS to ECU has two contacts.

Check voltage on removed connector and contact ON. Relative to ground one pin should read 0 volt while the other should read 5 volts.
If lower than 5 volts the wire from ECU is probably pinched somewhere.

Check electrical resistance between sensor's contacts. At 20°C it's around 3520 ohms. The higher the temp, the lower the resistance. Refer to table found in service manual.

Check electrical resistance between contacts and ground. It must be a open circuit.

Daniel

KING_3 · Post by **KING_3** » Wed Jun 04, 2008 4:51 am

thanks MM, daniel,

yup, i know which one is for the gauge and which is for the ECU. that one in the picture was the one i was checking.

can't remember if i already tried measuring the voltage on the connector while it is disconnected. Maybe i'll just try to check again. the only thing that discourages me is the difficulty of reaching in for the connector

i have to get under the car and fully extend my arm up, while getting around other components

Daniel · Post by **Daniel** » Wed Jun 04, 2008 5:02 am

Another quite crude method is watching sensor's voltage at ECU while snipping the relative cable. This will reveal if it's ECU problem. Leave enough cable lenght to connect it again.

Daniel

Daniel · Post by **Daniel** » Wed Jun 04, 2008 5:04 am

Another quite crude method (not recommanded

) is watching sensor's voltage at ECU while snipping the relative cable. This will reveal if it's ECU problem. Leave enough cable lenght to connect it again.

Daniel

kopisti · Post by **kopisti** » Wed Jun 04, 2008 8:42 am

After checking and cleaning most of the wiring on my Lanos I noticed that my temp gauge overturned a full revolution on the dash. It stays there doesn't matter if I disconnect the batttery or fuses just like the fuel gauge. Any idea what could cause this?

KING_3 · Post by **KING_3** » Thu Jun 05, 2008 4:25 am

Daniel wrote:Another quite crude method (not recommanded ) is watching sensor's voltage at ECU while snipping the relative cable. This will reveal if it's ECU problem. Leave enough cable lenght to connect it again.

Daniel

don't get what you mean by "snipping"?

Daniel · Post by **Daniel** » Thu Jun 05, 2008 7:29 am

KING_3 wrote:
Daniel wrote:Another quite crude method (not recommanded ) is watching sensor's voltage at ECU while snipping the relative cable. This will reveal if it's ECU problem. Leave enough cable lenght to connect it again.

Daniel
don't get what you mean by "snipping"?

You are right! Doesn't mean anything.

Please read "cut".

Pir0 · Post by **Pir0** » Thu Jun 05, 2008 8:08 am

Lol yeah, snipping's just a slang word for cutting :P