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I finally pulled all the tape off the wiring harness, and cannot see any obvious problems in the wiring harness. I am still dealing with a faulty TPS signal that shows up as an error code that is low voltage for more than 2 seconds, and then locked voltage return of 2.2 volts. I don't know, but imagine that this is a default value. Anyway, I am trying to reduce the number of wires in the harness to simplify the wiring. I would like to run all the sensor ground wires to ground rather than route them back to the ECM. I plan to run a ground wire from the battery in the trunk to the engine block, and the ECM is grounded at the battery, so it seems as if grounding the sensors to the block should keep the sensor grounds and the ECM grounds in the same ground plane.

Also, I think I am going to snip off all the NOS circuit wires from the ECM. There are about 5 or 6 of them. If I take out the sensor ground wires, and the NOS wires, then I will cut the number of wires down by almost half. I cannot imagine ever wanting to combine NOS with the Turbo. Anybody see a problem with this overall plan, either grounding the sensor wires to the block, or eliminating the NOS wires?

I will get a new GM TPS pigtail, and wire that into the tps circuit to minimize the possibility that my TPS signal problems comes from a bad connector. The thing is, it will run OK for while, and then get flakey. The other thing is, the TPS shares common leads with the other sensors, and they all are returning good values, so it kind of looks now like this ECM is going back to Accel for another repair. But I have to do this wiring fix up first so I can be certain the problem is not on my end. I guess there is a possibility that one of the wires has a break somewhere under the insulation, but this seems highly unlikely to me.
Sam

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I'd start by tracing the TPS voltage back to the ECU. See what sort of volts you get on the TPS signal pin with 12 volts on its supply line and its return line grounded. Maybe have someone shake the wires on the engine while you're doing this. This might turn up something about the TPS voltage, or at least help you figure out which end the problem is on.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Sam my SDS system works by providing the control switching on the "grounding side" of the circuit. That is, switched power to an item and then the ECM grounds it internally to activate the circuit. Make sure your system doesn't work this way.

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Cheers!
Al T

Accel said I can just ground the return wire from the sensors. They are all common, to the same pin. Your sensors must be grounded through the sensor. That would work essentially the same way, I think. The intermittant nature of this, of course really makes it hard to diagnose. When I check them, the wires seem to be good. The only TPS wire that is not common to other sensors is a brown wire to the center tap. It has it's own pin, and would be the most suspect, since the other sensors seem to work reliably at this time. Of course the connector could be problematic as well.
Sam

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Does anybody have a recomended way of tapping into an insulated wire to test it? The shop, Total performance stripped the wire back just slightly somehow on the ingnition leads right at the ECM, and then did not tape over them,thus leaving them bare for a short distance. This seems like a risky practice. I have also been told it is bad practice to pole through the insulation with a pointed probe. Any standard practice out there I need to know about? What is recommended by the pros, or good hobbyists? Also, is there a recommended practice, or material for reapplying some insulation neater than tape to any wire I have exposed through the insulation. Heat shrink tubing won;t work at this point because the wire is still hooked up. Is there a GOOD liquid insulation that can be painted on? Thanks.
Sam

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How special are the connectors? I've added a short section of wiring with male/female ends on it so I can tap into wiring for testing, just remove when done testing.

Forgot the name of it, but there is insulation in a can you paint/goop on. Liquid vinyl, Liquid tape,..... something like that....

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

There are special tools made for back probing connctors. Cutting into insulation is a no-no.

Liquid Tape, as mentioned above, would be a good repair.

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DynoDave
1970 Plymouth Duster
1972 Dodge Charger Rallye
1977 Chrysler Cordoba
WPC # 12304

Are these tools available at electronics stores, or auto shops? Can you perhaps describe the tools, and how they work. What should I be looking for? I guess I can go to the local lighting supply shop down the street from work and ask them.
Sam

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