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My 1997 CSE Turbo is exhibiting some odd ignition behavior. Intermittently, less so now, it will not turn over. It cranks like it very much wants to start but does not.

When this occurs the gauge cluster does not light up. Oil pressure, ABS light are very dim. The fuel gauge does not lift up. If I turn the headlight switch to the on position the system seems to engage and the car will turn over and start.

The volts seem to been in the 7-10 range when the car is turned on. When driving I notice times the volts will drop from 13.8-14 to 12-13. The headlights dim then the volts go back. Not sure if these are related.

The car is an Automatic with 97K miles on it.

Any input would be kindly received.

Kiernan
 

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Take off the battery cables and check your battery cables are clean inside the ends where they attach to the battery posts. Clean with a wire brush (a special design of brush with two parts is available to speed this up ) Clean the battery posts also. Re attach the cables and torque firmly but not too tight, lead deforms under pressure so excessive torque does not help. Seal the terminals with a small amount of petroleum jelly to keep air and moisture out or terminal spray if you can find any.

If the battery is more than four years old have it load tested before you bother cleaning the terminals. 90% of starting issues are due to a failing battery. 99% of battery failure is due to age. Five years is good service from a battery in the engine compartment of a turbo. Heat kills batteries, not load.

Next suspect your starter. Have it tested.

Then the ignition switch or the main ignition relay may be failing.
 

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The volts seem to been in the 7-10 range when the car is turned on.
I had a similar issue with my 1995 CS about 2 months ago.

For about a week, when I started the engine, I noticed the digital volt meter on the dash read about 7 volts. After the engine started, it would go up to normal voltage range. I thought nothing of it, until the engine would not even crank over.

The instrument cluster would also be very dim, like yours. I did some reading in the wiring FSM, and read that the digital volt gauge on the dash reads the voltage going out from the ignition switch to power the fuse bus. I can't remember if it is the "+15" or "+20" circuit from the ignition switch.

I had also checked the battery and connections as Superaero stated to you. I found nothing to cause a voltage drop like that. Then I went after the ignition switch itself, and found that the electrical portion was bad. Replaced it and all is well. The dash volt meter reads normal cranking voltage every start-up.


I would suggest doing some electrical diagnostics like Superaero states, before replacing any parts.
 

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Sounds like this is no longer an issue, but just as info:


To show the battery positive voltage on the display, the Electronic Display Unit (EDU) control module registers the voltage from the ignition switch +15 lead at 1 second intervals.

The EDU control module measuring range is 7.5 to 16 V .

When the engine is started, the battery positive voltage is shown on the display. The value displayed is the lowest voltage measured while the starter motor is turning the engine.

When the car has traveled 10 to 15 meters , the display reverts to the previously selected mode. Or you can just scroll through the display - by pressing the INFO button repeatedly - until the battery voltage is once again indicated.

So, given that, the following would be considered normal:

The volts seem to been in the 7-10 range when the car is turned on. All of my 9K's do that - all of the time.

On the other hand the next statement would not be considered normal and would suggest the alternator brushes are nearing the end of their useful life (the brushes are part of the voltage regulator assembly):

When driving I notice times the volts will drop from 13.8-14 to 12-13. The headlights dim then the volts go back.






But, the description of operation and your observation as below, make the diagnosis more nuanced.

Voltage supply and grounding of the EDU:

The Electronic Display Unit (EDU) control module is supplied voltage from +30 and +15. +30 gives power feed and +15 is used to start (boot) the control module.

Voltage is fed from +30 via fuse 17 in electrical distribution box 22A to pin 1 on the control module. +15 is fed directly from the +15 distribution terminal to pin 37 on the control module.

The control module works over the range 7.5 - 16 V .

Grounding points
The control module is grounded via pin 21 to grounding point G8.

When this occurs the gauge cluster does not light up. Oil pressure, ABS light are very dim. The fuel gauge does not lift up. If I turn the headlight switch to the on position the system seems to engage and the car will turn over and start.


Because the control voltage supply (which is also the monitored/displayed voltage) to the EDU is fed from the +15 bus - and the +15 bus is energized by the the RUN contacts within the ignition switch - as is the exterior lighting relay, that could very well indicate a failing ignition switch


Turning the headlights on may be causing the contacts within the ignition switch to heat up and make a better connection. Enough of a connection to supply the vital circuits - the ones necessary for the engine to operate - with sufficient power for starting.
 
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