I have been having problems with my CTS for a while now and I have finally decided that it must be something to do with the wiring. I have gone through three in the last 6 months. I have determined that there is a short or some other disturbance in the yellow wire coming off the sensor. I determined this by clearing the codes, connecting the black and yellow wires with a jumper, started car, got another code 15. I am told that this means it is a wiring problem. I then cleared the codes again and ran a jumper from the yellow wire to a good ground. Cleared the codes again, started it up and got another 15. My procedure tells me that this means that there is a problem with the yellow wire. Soooooo......I took my multi meter and did some tests. This is where you come in because when it comes to wiring and electronics, I am an idiot. I first tested for continuity on the yellow wire to the harness. It had continuity. The resistance on this wire was .1-.2 ohms with the ignition off. I couldnt get a value when the car was running, the meter would switch between k ohms and m ohms and stay at 0. The ground wire showed a resistance of 45 when the ignition was in the on position and 91 when the car was running. I then decided to get some values from the ECM pin #10, the CTS pin. On the yellow plug on the ECM pin 10 was as follows:

Top pin: 1.5 k ohms
Bottom pin: 1.7 k ohms

The black plug:
Top: 0
Bottom: 1.2 k ohms

I am not sure which one is the right plug as I am running an integrator for the SD conversion and the wires change colors. I am not sure if I am going about this right or if I have just made an *** of myself but I don't know where to go from here. Thanks.
bsa

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"If they do not run, Then they will die." - Stonewall Jackson

'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Comp Cam, Comp 1.6 Rockers, Lucas 23# injectors, Edelbrock headers, Flowmaster 3'' exhaust, gutted cat, Mallory coil, Mallory HyFire IV ignition box, Mallory Sidewinder 8mm wires, Autolite platinum plugs, K&N filters, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter

 

That was a little confusing, but I don't think you did that test right.
The CTS is simply a thermosister. The computer sends 5volts on one of the wires and the other wire is the return to the computer which basically tells the computer what resistance the CTS measures. As the CTS gets warmer the resistance goes down. If the reading from the CTS is above or below specs resistance wise then the computer will set a code.
If your CTS is new then it is unlikely to be bad (but possible). It is also unlikely that there is anything wrong with the two wires going to the CTS.
It is more likely that there is a problem with continuity between the ECM plug and the ECM itself.
That test you did by grounding the yellow wire would definatly set a code as a short-to-ground. That would make me think there is no continuity problem with the yellow wire.
However you may want to retest the other wire for an open between the sensor plug and the ECM side of the ECM plug.
That's all I can think of right now besides a possible ECM problem.
good luck


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*I do custom performance mods on Edlebrock Performer carburetors (dualplane intake mods in the works),
White 1986 Irocz, 305/383 with Edlebrock Performer-RPM intake and Performer #1407 carburetor, +110hp shot of crack, 700R-4 tranny, 3.25:1 rear, Mcreary Road-Stars, SLP-stainless 1.75" shortie headers & Y-pipe, single 3" Borla exhaust, Linginfelter-TPI camshaft part number 74216 pulls 17" vacuum solid. Cam specs 213/219 @.050 114-LSA, .462/.470 lift @1.5:1 ratio. MSD-6AL, billet distributor, multi-retard, blaster-3 coil, and RPM switch.
N/A runs 10.9 @124,
Crack-runs 10.3 @135
haven't run at track since Oct-99

 

oh and if you did replace the CTS, then did you also replace the sensor plug?

another possible open.

 

ok, like I said, I don't understand electrical stuff at all. All I know how to do is touch the multimeter to wires, and it sounds like I'm not even doing that right. I did replace the sensor plug, twice. Is there anyway that I can test the ECM to determine if that is the problem? Of course, it may be the integrator for the SD. If it is a continuity problem between the wiring harness and the ECM what will I have to do?? Replace the whole harness???
bsa