randman2011
10+ Year Contributor
- 552
- 282
- Feb 26, 2012
-
Indianapolis,
Indiana
Is there anything in between the ECU connector and the ISC connector that could cause an open circuit? I'm measuring voltage at the ECU connector but all four signal pins in the ISC connector are 0V/open. As a sanity check, I have also confirmed that neither the current ISC nor two BNIB units respond when plugged in. I've found lots of threads about problems with the ISC valve itself but nothing that I have seen mentions problems with the harness.
I used to get CELs for ISC problems and had all sorts of cold start issues. I bought some spare valves, but for other reasons ended up going Megasquirt before I investigated further. Now Megasquirt gives me the ability to set the ISC1A/B and ISC2A/B lines manually and I can confirm 12V at the Megasquirt, in the adapter harness, and at the factory ECU 26 pin connector but I get nothing on pins 1, 3, 4, and 6 at the ISC.
This car has a history of harness problems; I've repaired the fuel injector wires three times since I got the car in 2018. Those wire breaks were all pretty easy to diagnose and were in the length of harness between the thermostat housing and the injector connectors themselves. Since it's a lot harder to jiggle the harness to identify the problem spot for the ISC, I'm hoping that there's an easy solution to this before I just run four new wires to the engine bay or start shopping for a 2gb engine harness or lay down the money to go mil spec on just a daily driver.
I used to get CELs for ISC problems and had all sorts of cold start issues. I bought some spare valves, but for other reasons ended up going Megasquirt before I investigated further. Now Megasquirt gives me the ability to set the ISC1A/B and ISC2A/B lines manually and I can confirm 12V at the Megasquirt, in the adapter harness, and at the factory ECU 26 pin connector but I get nothing on pins 1, 3, 4, and 6 at the ISC.
This car has a history of harness problems; I've repaired the fuel injector wires three times since I got the car in 2018. Those wire breaks were all pretty easy to diagnose and were in the length of harness between the thermostat housing and the injector connectors themselves. Since it's a lot harder to jiggle the harness to identify the problem spot for the ISC, I'm hoping that there's an easy solution to this before I just run four new wires to the engine bay or start shopping for a 2gb engine harness or lay down the money to go mil spec on just a daily driver.