Redi2RocZ

Hi Guys,

I have replaced my CTS sensor ('86 Tpi 305) but my fan (single fan system) is running way under the 220 mark. Seems to fire up at 150/170 and then proceeds to cool the engine down but dosen't stop running, just carrys on cooling down. I got a Code 15 but the CTS is new.

(I presume that the CTS sensor switches on the single cooling fan when it reaches the pre-determined temp?)

The SES light comes on and stays on when this happens.

Do you think my Relay could be shot (near to the battery/side of radiator - am I right with the position/location - is this the correct relay?)

I think that I may have a bad ECM, would this cause this sort of problem?

Any info or thoughts gratefully received.

Tim Burgess

Sounds like there is an intermittant short to ground in one of the CTS wires.

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Tim

1992 Z28, 305 TPI 5 speed, 12.1 sec @ 114.7 mph

1984 Berlinetta 305 TPI Auto, 13.8 sec @ 99.7 mph

Redi2RocZ

Tim, not being the electrical type, what should I do to check out your theory?

I have a DMM so I could perhaps measure something maybe?

Do you think this could be something to do with the ECM?

I don't seem to get an SES light all the time when using the paperclip although the fan starts up and the IAC pushes home.

Hopefully the ECM isn't Fubar?

What do you think?

Thanks for any further advice.

mtccl

Definitely a grounding problem. Could be a bad CTS you installed. Remove, check, reinstall...problem persists, get another CTS. My 87 TA fan relays are on the radiator support shroud in front of the airbox, passenger side. One for each fan. Standard 4 prong relay.

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87 TA, 305 TPI, Custom CAI, K&N, ACCEL 8mm wires,ACCEL Super-coil, ACCEL Plugs, JET TPI Airfoil, Cherry Bomb Muffler, 160* thermostat
The Phoenix Project..click to see my project car
Trans Am stuff and GIRLS, GIRLS, GIRLS!!!!!

Tim Burgess

The CTS should have yellow & black wires going to it. The black is ground & the yellow is the sensor output to the ECM. Most likely, if the sensor is in fact good, the yellow wire has an intermittant short to ground - look for an open in the wire insulation where it may be rubbing on something, or there may be a short at the plug at the end of the wires. When the problem occurs, try mowing the wires around & see if the fan turns off, or turn off the ignition & measure the resistance from the yellow wire to ground - it should not be zero - if it is, then try removing the ECM & see if the short persists. If the short is still there, then the short is in the yellow wire somewhere.

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Tim

1992 Z28, 305 TPI 5 speed, 12.1 sec @ 114.7 mph

1984 Berlinetta 305 TPI Auto, 13.8 sec @ 99.7 mph

88 SC

Maybe it's just me thats way off here, but did you replace the coolant temp switch on the intake manifold or the fan coolant switch on the passenger side head ( below the exhaust manifold) The fan coolant switch has one wire that grounds the circuit at a predetermined temp and energizes the fan relay. On my 88 Sport Coupe that relay is on the driver's side firewall. From what I understand, the CTS (Black and Yellow wire) sends temp signals to the ECM but does not control the fan. Sounds like you may have replaced the wrong sensor.

Redi2RocZ

Thanks for the input guys.

I have replaced the sensor (CTS, it is located below the thermo housing and is next to the cold start injector sensor)

I thought that the ECM via the CTS controlled the Single Fan on a Tpi Camaro?

Perhaps somebody could clarify this?

Thanks again.

Tim Burgess

I believe that the ECM does control the fan, via the CTS, in your application. The temperature sensor in the passenger side cylinder head is used to control the secondary fan in dual fan systems, with a TPI setup.

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Tim

1992 Z28, 305 TPI 5 speed, 12.0 sec @ 114.8 mph

1984 Berlinetta 305 TPI Auto, 13.8 sec @ 99.7 mph

JAY87GTA

According to my Chiltons, the ECM controls the relay. I'd do like tim suggested and check for an intermittent ground. Probably the relay is sticking closed. You might also want to check for power getting to the relay coil when it isn't supposed to be, you might be getting power from somewhere else in the wiring harness that your not supposed to get, causing the relay to stay shut.

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'87GTA w/ SLP Cold Air, MSD Coil, Airfoil, Gutted MAF, AFPR, TES Headers, HI-FLOW CAT, Flowmaster Catback, Energy Suspension Master Bushing Kit