Coolant Temp. Sensor issue
#1
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
Coolant Temp. Sensor issue
I am getting a code 15 and i already had a new CTS on the car and so i checked the connection and it seems fine, and i changed the sensor and i still get it after i reset the battery, i checked the voltage across the terminals and it was 5.v(well 4.97) the car heats up fairly fast and i dont see why, but sometimes the light will go out so im not sure what is going on there. maybe i need to clean up the connector a bit or something. it seems to run alright runs kinda choppy at start up but when it gets a little warmer itll stay running easily. is this possibly a simple connection problem? or is there something else to a code 15?
#2
Since you have a new CTS, and have a 5V reference voltage at the sensor, you need to check the ECM edge connectors. You should also check the engine cround strap and grounding connections at the RR of the engine. For some reason, the ECM is seeing too much resistance across the sensor (open circuit).
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
Originally posted by Vader
Since you have a new CTS, and have a 5V reference voltage at the sensor, you need to check the ECM edge connectors. You should also check the engine cround strap and grounding connections at the RR of the engine. For some reason, the ECM is seeing too much resistance across the sensor (open circuit).
Since you have a new CTS, and have a 5V reference voltage at the sensor, you need to check the ECM edge connectors. You should also check the engine cround strap and grounding connections at the RR of the engine. For some reason, the ECM is seeing too much resistance across the sensor (open circuit).
#4
The "edge connectors" are the harness connections at the ECM itself. They can become dirty, loose, and oxidized. You can often "freshen up" the connections simply by removing and reconnecting the plugs a few times. The wiping action of the contact leaves or pins over the ECM card edge or header connectors (depending on ECM type) is often enough to clean the dirt and oxidation from the connectors and provide good contact.
Since I'm guessing you have the CCC type ECM, it likely has raw circuit board edge connectors, like this type:
Since I'm guessing you have the CCC type ECM, it likely has raw circuit board edge connectors, like this type:
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
Originally posted by Vader
The "edge connectors" are the harness connections at the ECM itself. They can become dirty, loose, and oxidized. You can often "freshen up" the connections simply by removing and reconnecting the plugs a few times. The wiping action of the contact leaves or pins over the ECM card edge or header connectors (depending on ECM type) is often enough to clean the dirt and oxidation from the connectors and provide good contact.
Since I'm guessing you have the CCC type ECM, it likely has raw circuit board edge connectors, like this type:
The "edge connectors" are the harness connections at the ECM itself. They can become dirty, loose, and oxidized. You can often "freshen up" the connections simply by removing and reconnecting the plugs a few times. The wiping action of the contact leaves or pins over the ECM card edge or header connectors (depending on ECM type) is often enough to clean the dirt and oxidation from the connectors and provide good contact.
Since I'm guessing you have the CCC type ECM, it likely has raw circuit board edge connectors, like this type:
#6
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
well that wasnt the problem, my engine light goes off and on when im driving and doesnt seem to affect anything really, but lately its been staying on. this is odd. any other troubleshooting?
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Car: Check The Sig
Hrm...book says here to dissconnect CTS and jump the terminals together. Start engine and run for one min or untill SES light comes on and then check code.
If you get code 14, the connection or the sensor is bad
if you get code 15, probe the yellow wire (ckt 410) with voltmeter to ground. It should be 4-6 volts.
If it is 4-6 volts, the sensor ground circuit is open or faulty ECM connection, or bad ECM
If its not, the yellow wire (ckt 410) is open, fault ECM or bad ECM.
If you get code 14, the connection or the sensor is bad
if you get code 15, probe the yellow wire (ckt 410) with voltmeter to ground. It should be 4-6 volts.
If it is 4-6 volts, the sensor ground circuit is open or faulty ECM connection, or bad ECM
If its not, the yellow wire (ckt 410) is open, fault ECM or bad ECM.
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Car: 85Z28 87GTA 91GTA 98SS
Engine: SBC, LS-x
Transmission: T-5, 700-R4, T-56
Pencil eraser is good for cleaning those contact points you can reach. They don't look bad in the pic. Electronics cleaner is good for the ones you can't reach.
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
Originally posted by bigals87z28
Hrm...book says here to dissconnect CTS and jump the terminals together. Start engine and run for one min or untill SES light comes on and then check code.
If you get code 14, the connection or the sensor is bad
if you get code 15, probe the yellow wire (ckt 410) with voltmeter to ground. It should be 4-6 volts.
If it is 4-6 volts, the sensor ground circuit is open or faulty ECM connection, or bad ECM
If its not, the yellow wire (ckt 410) is open, fault ECM or bad ECM.
Hrm...book says here to dissconnect CTS and jump the terminals together. Start engine and run for one min or untill SES light comes on and then check code.
If you get code 14, the connection or the sensor is bad
if you get code 15, probe the yellow wire (ckt 410) with voltmeter to ground. It should be 4-6 volts.
If it is 4-6 volts, the sensor ground circuit is open or faulty ECM connection, or bad ECM
If its not, the yellow wire (ckt 410) is open, fault ECM or bad ECM.
#10
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
well i jumped it across the wires and i reset my codes and i ran the car up to about 190 i drove it around and everything and the engine light didnt come on at all.
#11
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
ok i checked the codes anyways and it came up with code 14, but iv replaced the sensor a few times already. so the connection must be bad....or do you think i need to put another ground cable in from the engine to the body?
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Car: 88' IROCZ
Engine: 388 TPI Motown 350 Race block
Transmission: 700R4
Axle/Gears: 2.77
Originally posted by TPIMarow6.6
ok i checked the codes anyways and it came up with code 14, but iv replaced the sensor a few times already. so the connection must be bad....or do you think i need to put another ground cable in from the engine to the body?
ok i checked the codes anyways and it came up with code 14, but iv replaced the sensor a few times already. so the connection must be bad....or do you think i need to put another ground cable in from the engine to the body?
#13
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
Originally posted by rgarcia63
I put in a new CTS before I did the cam break-in, 2 weeks later I get a code 15, I do the diagnostics, and don't find anything wrong in the circuits, so I replace the sensor, no more code 15.
I put in a new CTS before I did the cam break-in, 2 weeks later I get a code 15, I do the diagnostics, and don't find anything wrong in the circuits, so I replace the sensor, no more code 15.
#14
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It's a wiring/connector issue of some kind, I'm sure. I had an intermittent code 14 on an old Blazer (CTS reading too high). It wouldn't do it while idling in the driveway but if you accelerated under load it would often pop a code.
Turned out that one of the CTS wires in the harness had chafed against an engine bracket and was intermittently shorting against it, but only when the engine torqued over under load. I pulled it away from the bracket, repaired it, wrapped a little tape around it and never had the problem again. Guess how long it took me to diagnose THAT little bug!
I suspect you are having some sort of similar problem- a broken/chafed/pinched wire somewhere, or the connector itself is bad.
Turned out that one of the CTS wires in the harness had chafed against an engine bracket and was intermittently shorting against it, but only when the engine torqued over under load. I pulled it away from the bracket, repaired it, wrapped a little tape around it and never had the problem again. Guess how long it took me to diagnose THAT little bug!
I suspect you are having some sort of similar problem- a broken/chafed/pinched wire somewhere, or the connector itself is bad.
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
Originally posted by Damon
It's a wiring/connector issue of some kind, I'm sure. I had an intermittent code 14 on an old Blazer (CTS reading too high). It wouldn't do it while idling in the driveway but if you accelerated under load it would often pop a code.
Turned out that one of the CTS wires in the harness had chafed against an engine bracket and was intermittently shorting against it, but only when the engine torqued over under load. I pulled it away from the bracket, repaired it, wrapped a little tape around it and never had the problem again. Guess how long it took me to diagnose THAT little bug!
I suspect you are having some sort of similar problem- a broken/chafed/pinched wire somewhere, or the connector itself is bad.
It's a wiring/connector issue of some kind, I'm sure. I had an intermittent code 14 on an old Blazer (CTS reading too high). It wouldn't do it while idling in the driveway but if you accelerated under load it would often pop a code.
Turned out that one of the CTS wires in the harness had chafed against an engine bracket and was intermittently shorting against it, but only when the engine torqued over under load. I pulled it away from the bracket, repaired it, wrapped a little tape around it and never had the problem again. Guess how long it took me to diagnose THAT little bug!
I suspect you are having some sort of similar problem- a broken/chafed/pinched wire somewhere, or the connector itself is bad.
#16
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Engine: 355 TPI
Transmission: 700R4
Hi, just curious if you ever solved the problem. I'm having a similar problem with an intermittent code 14. Replaced the sensor, no change. Replaced harness, no change. I guess it must be the connection at the ECM or the wires in between.
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Car: 85 Camaro Z-28
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no actually i havnt figured it out, if i let my car sit over night, there wont be an engine light till like 1 minute of it running. i loosened the wires so they wernt touching the block, i changed the sensor, i might try putting another body to engine ground.
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Engine: 355 TPI
Transmission: 700R4
Well, I checked the resistance on the cts today and compared it with the resistance/temp chart floating around on the boards. Seemed fine to me, although I only checked it at one temperature (~90F)...1.7k.ohms. I didn't appear to be getting any voltage at all through the connector. I'm gonna check the continuity of the wire and check the computer connection tomorrow. This is getting ridiculous. I probably need a new ECM, knowing my luck. F.
Well let us know if you make any progress with your problem.
--AA
Well let us know if you make any progress with your problem.
--AA
#19
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Car: 85 Camaro Z-28
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yeah i dont have the foggiest, since i already changed the harness i think its probably my engine ground so i have to do that sometime this weekend and see what goes on. let me know how your troubleshoothing ends up.
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Engine: 355 TPI
Transmission: 700R4
Hey, I ended up replacing my computer, which seems to have solved the problem. I haven't been able to verify this with a scanner yet to make sure the ECM is interpretting the correct temperature, but I have not gotten code 14 since I replaced the computer...been over a week. My car also idles pretty steady and low now which didn't do before.
Here's my thread...don't remember if I gave you this before or if you have looked at it. But, maybe something there will help you if you are still having troubles with yours.
https://www.thirdgen.org/techbb2/sho...hreadid=289744
--AAron
Here's my thread...don't remember if I gave you this before or if you have looked at it. But, maybe something there will help you if you are still having troubles with yours.
https://www.thirdgen.org/techbb2/sho...hreadid=289744
--AAron
#21
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
let me know when you get it checked out. was you car doing the same thing as mine? bucking at slight throttle and almost nothing at 1/4 or more throttle?
#22
Originally posted by HalfInchWrench
Pencil eraser is good for cleaning those contact points you can reach. They don't look bad in the pic.
Pencil eraser is good for cleaning those contact points you can reach. They don't look bad in the pic.
Connections are the least of the problems on that ECM. Did you notice the upper LH corner of the board, where the smoke was allowed to escape? Easy fix, and common problem on ECMs that have been exposed to overvoltage.
Marrow,
Did you tap-test the ECM? May have a failing solder joint there.
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Car: 85 Camaro Z-28
Engine: 6.6
Transmission: 5-speed
Originally posted by Vader
Marrow,
Did you tap-test the ECM? May have a failing solder joint there. [/B]
Marrow,
Did you tap-test the ECM? May have a failing solder joint there. [/B]
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