[s-cars] CPS Question

[racingiron at comcast.net]

> When you turn the key on, does the MIL (what you note as the CEL) 
> NOT illuminate and the engine does not start? And, later when you 
> turn the key on, does the MIL illuminate and the engine starts? 

Both correct. When the car is behaving normally, I get the MIL at first key turn before starting. During these no-start fits, the MIL does not light up. 

> If the above sequence of events is the scenario that is occurring with 
> your car, that is an indication that the ECU is not communicating for 
> the no-start episodes. 

My suspicion exactly. I just got back from some wiring checks. Pin 30 on the ECU connector is shown on the Bentley diagram as going directly to ground, but I'm not getting that. Specifically, it's #201, which Bentley calls "ground connection -5-, in engine compartment wiring harness." 

A few other items use this ground point: knock sensors, coolant sensor, TPS, IAT, and... wait for it... the pressure sensor (that explains the boost gauge weirdness!). I checked the wire at the TPS and it also doesn't have continuity to ground. So, I think I've found the culprit, only I HAVEN'T found it yet. Anyone know where "ground point -5-" is located? According to the diagrams, most of these wires are green/black, not brown, so this is not one of the normal ground points I'm familiar with. 

Eric R. 
'86 urq 
'92 urS 
'93 urS