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Discussion Starter · #1 ·
I'm fault diagnosing a 1986 16V T and need access to the relays above the ECU. What's the best way to jumper one of the Relays? Do I need to remove the lower portion of the dashboard to identify the sockets?
 

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Ive found it best to 1) remove Jetron. ECU, then 2) remove the ECU bracket chassis from the car body...........relays are attached to the bracket.
Good luck!
 

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BTW, there is enough wire behind the relay sockets you can have them hanging down even after you put the covers back on. That is what I did in my white Saab: i can now reach them any time I want.

Of course that meant I stopped having any problems related to them... :confused:
 

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Discussion Starter · #4 ·
Much appreciated. I've got a Twin dilemma. Both 900T's fail to start. It's funny how these things appear out of the blue. I've got a "check engine light" on the 1989 and a no start condition. I've got spark on both, yet no start.

1986T:
Car turns over but will not fire.
Starter works.
Battery new and charged.
Fuel in tank.
Cleaned Hall sensor contacts on Dizzys
Re-gaped and cleaned spark plugs. All 4 look proper.
Tried different coils, AIC's ,TPS. (un-scientific)
Not getting 12 volts at the injectors.
Cleaned contacts at fuel pump.
 

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Is your fuel pump coming on? Could be the fuel pump relay or (if it comes on initially but then shuts off) it could be not receiving a signal from the hal sensor indicating that the engine is running. Check the FPR - bypass is or swap in a known good one - see if that gets it going.
 

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Discussion Starter · #6 ·
I Jumped the fuel relay and tried swapping the 2 relays after disconnecting the Control circuit from the chassis. (plastic piece). I could not hear the fuel pump running. I cleaned the hall sensor contacts and jiggled it around a bit.

Swap a Fuel pressure regulator? (FPR.)
 

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Grab your trusty digital multimeter and check the voltage to one of the injectors with power on and the said injector not connected to the, well, connector. One of the pins should be 12v and the other 0. If you are getting 12V, then measure the continuity between the 0V pin and ground. It should be open. When you crank the engine it should pulse, as if it is trying to ground. If that is not happening, check pin 1 on the ECU. When the engine crank it should pulse (like 0 to 5V or something). That is the tach signal to the ECU.
 

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Hall sensor failed on mine `vert recently. No tach signal, no power (or eart to ECU) -> no start condition.

Connect a test light at coil`s signal wires (small contacts) and crank the engine. If it flickers, your Hall sensor and ignition module is good. If light is not lighting, Hall sensors, ignition module or wiring between them is shot.
 

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Discussion Starter · #9 ·
The tach bounces when trying to start. Should I rule that out? It started this morning for a second or 2. I've got the wooden cover off the shelf to access the fuel pump and Fuel Level Transmitter. Checked the ground at the alternator. Swapped Relays in the kick panel. The Bentley is getting quite a bit of use...

Edit: Fuel pressure regulator I have not tried. Thoughts?
 

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Discussion Starter · #10 ·
Update: The pumps on both turbos were getting 12 volts by jumping the fuel pump relays. I took a good battery and tested all the fuel pumps in the fleet. My 1986S was the only pump that I could get to run. So, I'm assuming a pair of fuel pumps...one the rotor type and the other a roller type.
 
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