Saab's electrical system


If you have worked on your Saab's electrical system, you may have noticed that the relays and electrical components terminals are numbered. By understanding this numbering system, you will know what to expect as a test result from that connector. Example, if you see a 30 this is a +12 volts all the time key on or off. Here is a list of terminal numbers and what they refer to. Remember pin numbers on computers/ ECU's do not apply to these descriptions. These are not 100% in all situations you really need the wiring diagram for any given circuit to properly diagnosis it. Although this list should give you a helping hand as to what terminals you should be testing, and under what conditions.

30 positive power supply 12 volts this terminal is hot at all times regardless of the ignition keys position.

X this is live 12 volts whenever the ignition switch is in the park , run or crank position.

15 12 volt supply with the ignition in the run or crank position.

54 this is 12 volt power when the switch is in the run position only.

50 this is 12v in the crank position only mainly to energize the starter

Now on relays you may find some other numbers. These numbers are the same on most relays but there are a few exceptions. You may also find numbers not mentioned here. I'm only listing the numbers that are most common.

87 this is the positive power going to the component being controlled by that relay.

87A this is the same as 87 except is for a second component the same relay may be powering

85 12 volt positive to activate relay

86 this is a ground for the activation coil of the relay.

31 this also is a ground for the activation coil of the relay.

TD engine speed signal in the form of a square wave.

TK 12 volt signal from terminal 50 engine cranking


(This article is meant to educate a consumer,or as a guideline for professionals. You can cause serious damage to your vehicle and/or cause yourself injury. Only those qualified should attempt repairs. I do my best to assure that the above info is correct but take no responsibility for any damages incurred.)


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