Buck268

First, what does it mean by 'Temp Low', is the coolant to cool, or is it not matching another reading.

and second, any ideas on how to fix it? I have already tried putting a new Coolant Temp. Sensor in (the one for the ECM, near the intake manifold).
Any help or suggestions would be great!

z28onTweenkies

im having the same problem. i've been having it for a few weeks now. there is a sensor on the block between the 1 & 3 cylinders with a wire going to who knows where. anyways, thats the coolant sensor, the coolant temp sender is on the thermo housing, ive changed it and it didnt make a difference. from what ive heard it could be a wiring problem to the sensor on the block. problem is im too lazy to jack my car up and find out. oh well.

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1987 LG4 Camaro z28

Performance
KN airfilter, flowmaster 80 series and catco high flow converter, 180* thermostat, edelbrock performer intake

System
Panasonic CQ-DF200U deck, fosgate speakers (hpc1369, frc2246), fosgate 400a4 amp

deadbird

z28,,,the one on the side in the head (1 green wire attached),, that's the gauge temp sensor, totally unrelated to ECM use.

The ECM CTS (coolant temp. sensor)is on the thermostat housing on a carb'd engine(like an LG4), and the front of the intake manifold on a TPI (no clue about TBI,,). While I've never had the problem,, I can give you a book diagnosis

Code 15 indicates the the ECM is seeing a high voltage on the wire to the CTS (the yellow wire)

Clear the codes & run the engine until the Check Eng Light comes back on. Does code 15 return ? If not , then the problem is intermittant & no repair is needed at this time.

If the code 15 returns, clears the codes, disconnect the CTS & and install a jumper between the terminals of the CTS (usually yellow & black wires). Start the engine & run until the Check Eng Light comes back on. Then pull the codes. Is there a Code 15 or 14 ?

If there is a code 14, the coolant sensor wiring harness is OK. Check the connection to the coolant sensor. Check the resistance in the coolant sensor. If both are OK, then replace the ECM.

If there is a code 15, the wiring harness has an open circuit. Clear the codes. Connect a jumper wire from the yellow wire of the sensor harness to the block ground. Start the engine & run until the Check Eng light comes back on. Pull the codes. If code 14 comes up, inspect the black wire on the harness for an open. If 15 comes up, inspect the yellow wire on the harness for an open. If either 14 or 15 were generated but neither wire has an open circuit, replace the ECM.

Maybe that'll help the both of you hunt down the prob.

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[This message has been edited by deadbird (edited October 15, 2001).]

Buck268

well, the harness is ok, brand new ecm (close to cost of dealer diagnoses, so what the hell...) - car runs very different - but the code 15 remains...what would be the part number fer an oem replacement?? maybe i have wrong CTS...

JPrevost

Have you tried reseting the ecm? To do so, either disconnect battery or unhook ecm. I think you can also unplug the ecm fuse but I don't know if that works. Leave it unpowered for a few minutes to make sure it's cleared.
For TBI, the CTS is also in the front part next to the thermo housing (in the intake manifold). The guage temp sensor is in the drivers side head, the passengers side head is the fan on/off switch.

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, Jon (350 TBI!)
91 Red My website

Buck268

uh, wtf? I had my ecm out fer about 5 to 10 minutes while checking wires...and either it didnt reset the trouble codes, or it is getting a 15 BEFORE I start the engine, when I put switch into "on" position. This cannot be good.