[Keyz]

Most of the case it's the ABS ball which is the culprit of hard pedal and ABS light "ON".
I've already changed this ABS hydraulic accumulator ball.
When key is turned on "accessories position", the pump doesn't make the usual buzzing sound when filling the ABS accumulator ball...
Nothings happen when jumping the ABS pump relay, with a jumper wire between pins 87 and 30.
So, I deduced that the pump is faulty. Is there a way to change this pump, without dismantle the whole ABS assembly unit: brake reservoir and master cylinder and accumulator ball?

 

[AUSSIE900]

Check the electrical connections at the pump , especially the earth point .

 

[Keyz]

@AUSSIE900
I know the main earth point at the bottom of coolant radiator, and other earth point like the alternator's earth point or ignition amplifier earth point... But I don't know where this ABS pump ground point is? Could you tell me, please?

 

[AUSSIE900]

look at the pump , to the front of the accumulator , you will see a Harness Connector and a 10mm bolt head that accomodates the earth point , a few black wires with ring terminals , They do get Cruddy .

 

[jvanabra]

Also check fuses, relay, and pressure sensor.

 

[Keyz]

@jvanabra
Fuses are OKAY.
How to test pressure sensor? By jump wiring it...?

 

[Keyz]

ABS pump could be seized up...

 

[AUSSIE900]

I think that is unlikely , I would be looking at the wiring and its triggers , perhaps follow the wring diagrams ( in the stickies at the start of the forum ) and determine what pins receive 12v and try a hot wire

 

[Keyz]

@AUSSIE900
I think the ABS pump grounds with the master cylinder's screws.

 

[Keyz]

I read the ABS wiring diagram, it shows that ABS pump fuse is grounded via two ground points: G25 (on gearbox) and G1 (next coolant radiator), for the ABS pump it shows that it grounds on G12 (ignition amplifier).

 

[jvanabra]

That seems right. By 1990 the wiring harness on the c900 was pretty refined.

lol

 

[Keyz]

I'm stuck with this ABS light problem... I'm pretty sure the pump motor is the culprit! Is there a way to unbolt it, without unbolting the whole master cylinder?

 

[AUSSIE900]

I took a look at an Assembly I had amongst my spare parts .

It would appear that the winding component of the pump motor can be removed In Situ .
There are 2 torque head screws directly below the Accumulator that go though the casting that houses the pumps gears to the Plastic body of the pump winding . At the opposite end is a locating post .
It would appear that if you remove those 2 screws the winding will slide away from the pumps cast gear housing.
Have you tried a direct 12 v feed at the pump motor , i.e hotwire.

 

[Keyz]

Thanks for your reply AUSSIE900.
You mean "torx" head screws?
No I didn't test to put direct feed on the motor. I don't see where the pump motor's socket is located.

 

[AUSSIE900]

Thanks for your reply AUSSIE900.
You mean "torx" head screws?
No I didn't test to put direct feed on the motor. I don't see where the pump motor's socket is located.

Yes Torx , there is a connector at the pump . I dont know the pinouts but you should be able to work that out from the wiring diagram . If needed I can get a pic , but it should be pretty obvious

 

[Keyz]

Ok, I'll watch the diagram. Your ABS assembly is unmounted from your 900?
Could you get a pic of the position of the bolts, please?

 

[Keyz]

From ABS diagram as I can see, pin 2 of ECU, controls pin 4 of the ABS pump relay.

 

[jvanabra]

I think you're looking at the wrong end of things - you need to be looking at the pump side of things, not the ECM. The idea is to power the pump directly from the battery (or some other 12v source) to verify it's capable of running.

 

[Jim Mesthene]

SAAB says: if possible, do all testing from the back of the disconnected ECU plug, after removing the cover; that's where the terminal numbers are printed and you can see the wire colors. This is important when running hot or ground wires that might fry something.
That way you test the entire circuit, including the wire harness and connectors.

 

[a9548925559]

There is a listing for the pressure switch on ebay that has diagnostic instructions. search saab 8994071.