Project Loki - 1988 classic SAAB turbo

[Jordan]

Sounds like either the tach signal is not reaching the ECU or the ECU is bad and not activating the FP and injectors. (What Drew said)

If the plugs are dry then you know the injectors are not firing and I wouldn't even mess around with checking the injectors. What version of LH does this car have?

[DrewP]

The back portion of the LH connector has two screws that hold the dust cover on so you can slide it back to probe the back of the pins with the ECU connected to it.

Easy way to tell LH version is the air mass meter - if it's got an aluminum AMM it's LH2.2, if it's black plastic it's LH2.4.

[Adrian Thompson]

Its an 88 so it should be 2.2. The AFM is alloybwith a plastic cover

[Adrian Thompson]

Just had a look. The plastic cover to the AFM says 'fuel injection corporation USA' molded I to it. I would have assumed it would have said Bosch. Does this mean its an aftermarket or reman unit?

[99Super]

Yup, that's a reman, I have one in my 85 SPG, but it won't keep the fuel pump or injectors from working.

[Jordan]

Just checking because 88 and 89 were a changeover year and 89 had a high rate of defect ECUs. LH 2.2 I don't think had the same problem, but you seem to be getting closer. The ECU grounding the 85 pins on the relay board (yellow and purple wire probably) when the engine is turning and the ECU has power.

[Adrian Thompson]

OK, last nights 'progress' between thunderstorms, mosquitos and family.

I could see an easy way to get to the back side of the connector. There isn't two screws, there's just one at one end and the cable coming out at the other end. Will investigate further if needed.

So, with the ECU removed and the ignition on I tested power to each pin Vs ground. With the jumper removed from the fuel pump circuit removed I had power to the following:
Pin 18 which I believe is the ECU power circuit. So it is getting power.
Pin 16 which I think it the AC circuit.
Then putting the jumper jack in so the fuel pump circuit is getting power I still got power to pins 16 & 18, but additionally I also had power to:
Pin 1 which I believe is the Ignition pulse signal, i.e. the tach signal so I think it’s getting what Jordan said I needed. That means the ECU maybe toast correct?
Pin 4 which I think is the Automatic trans, which doesn't make sense as this is a manual car
Pin 20 which I believe is the O2 sensor

Do I have these pin outs correct? I don’t have a full list of all pins, this is based off ‘Table k. LH 2.2 Electrical Tests’ on page 240-20 in the Bentley manual.

I’m not going to get a chance to head out to the car again until either Sunday or Monday night, but I think I need to sit down and read the full diagnostic procedure through several times before I head out to the garage again. But it’s looking like a dead ECU, yes?

If I have managed to somehow kill the ECU, does anyone have a spare LH2.2 ECU for sale? If so please let me know either here or via PM how much inc. shipping to Zip 48025

Thanks guys.

[Adrian Thompson]

Hang on, looking at the table in Bentley again it says Pins 1 and 25 are the Ignition Pulse circuit, not just pin 1 I mention above. It also says the test is which cranking. So, that being the case, I may or now may not have a dead ECU.

I think I really need to get the ECU Connector cover off and check from the back side while it is plugged in and get a helper so I can crank at the same time.

[DrewP]

If you take that one screw out, you can push the connector's insulator out from the back, it sort of pivots out on a lock tab and then you can slide the dust cover and the rubber grommet up the wire loom to get access to the back of the pins.

Did you go thru the whole fuel injection fault tracing procedure in the Bentley? The very end of it is to diagnose a faulty ECU, at this point it makes sense to be systematic and do the entire procedure rather than just pick and choose probing contacts with things disconnected and with possibly suspect sensors and such. That's what I'd do at least.

[Adrian Thompson]

Wow, only 6 weeks for an update if not progress!

So, last night I got back to the car and took the advice above and started the Bentley trouble shooting guide. Despite the fact that I have 4 relays it appears they are all shot according to the test procedure! I do have continuity to the Air meter connector, but with the relay in no voltage so according to Bentley that 'probably means' the relay is faulty. As I say strange since I have 4 to try.

Anyway, all the relays I have are Bosch 0332 015 013. Now, the question what is really the difference between relays? There are a ton of different relays that appear to be the equivalent of 0332 015 013 from different people. The confusion comes from places like RockAuto that list some relays for multiple uses like the Injection control and fuel pump etc. But it doesn't list all the options for all uses so what gives? why can you apparently use relay 'A' for use x, y and z, but relay 'B' is only listed for use x and z while relay 'C' is listed for y and z? Why aren't they all acceptable for x, y and z? Doesn't that make sense.

I want to get a new relay for both the computer and the fuel pump circuit and a spare, so three relays, ideally all the same. But which one? especially as prices seem to range from $10 - $40 for effectively the same apparent part.

thx for helping out a numbskull guys.

[DrewP]

Maybe your +12v distribution block isn't getting power to your relay socket - it's pretty unusual for relays to go bad.

Pull the relay out and put 12v across terminals 85 and 86, the relay should click. It doesn't matter which one you put positive or negative to, it should click just the same. You can just use a car battery and some wire if you're careful, or a 12v drill battery (or even up to ~18v if you don't have a 12v drill. A 9v battery might be enough to close the relay coil too.)

Terminal 86 usually has switched +12v when you key the car on. and terminal 85 gets switched ground. The main relay gets +12v and ground directly from the ignition switch, the fuel pump and ignition lock relays get it from the main relay I believe. You'll have to follow the wiring diagrams.

If your relays work, start probing at the relay sockets, check for the correct power and ground where 85 and 86 go, and you should have +12v at terminal 30 either always, or when you switch the ignition switch on. Terminal 87 is the 'outgoing' power to whatever is being switched. When 85 and 86 have ground, the relay connects the ouput terminal 87 with terminal 30. If the relay has two terminal 87's (usually 87 and 87a like this graphic below) then BOTH 87 and 87a get connected to 30 to send power to two different things.

A 5 pin relay like the bosch -013 ones you are asking about can be interchanged with any other standard 5 pin relay you can find in just about any car as long as the amperage ratings are the same. The -013 has two 15 amp circuits (stamped into the top of the relay). Some higher current relays have larger spades coming out the bottom and will not physically fit into your relay socket, but as long as the spade terminals are the same size you're pretty much guaranteed they are compatible.

FYI, newer Saabs and BMW's have nicer waterproof relays that are sometimes even diode protected (so you can't accidentally send ground to something that needs +12v to avoid shorting things out) that plug right into the Saab sockets. Pretty much any VW, Volvo, BMW, Mercedes, and lots of GM cars have relays that you can grab from, and they're usually like... $1 at junkyards.

[Adrian Thompson]

The power distribution block is getting power and so is the relay block. I don't know why I didn't think to jump the relay and listen. I'll do that this weekend. Thanks.

[Jordan]

A 5 pin relay like the bosch -013 ones you are asking about can be interchanged with any other standard 5 pin relay you can find in just about any car as long as the amperage ratings are the same. The -013 has two 15 amp circuits (stamped into the top of the relay). Some higher current relays have larger spades coming out the bottom and will not physically fit into your relay socket, but as long as the spade terminals are the same size you're pretty much guaranteed they are compatible.

FYI, newer Saabs and BMW's have nicer waterproof relays that are sometimes even diode protected (so you can't accidentally send ground to something that needs +12v to avoid shorting things out) that plug right into the Saab sockets. Pretty much any VW, Volvo, BMW, Mercedes, and lots of GM cars have relays that you can grab from, and they're usually like... $1 at junkyards.

The 5 pin fuel injection relays are sort of unique, you have to be careful to use one that has an 87 and 87B terminal instead of an 87 and 87A. The later one has a closed switch from 30 -> 87A when not energized and then closes on 87 when energized. The correct relay is open on both terminals and then closes on both terminals when energized. Using the wrong 5 pin relay will probably run the car , but not run the 02 sensor heater.

My understanding is that the diodes in the relays prevent "flyback" through the switched circuit. Which is the current spike that happens when the field collapses in the relay. It prevents damage to sensitive circuitry in the computers generating the switch signals.

[Adrian Thompson]

The 5 pin fuel injection relays are sort of unique, you have to be careful to use one that has an 87 and 87B terminal instead of an 87 and 87A. The later one has a closed switch from 30 -> 87A when not energized and then closes on 87 when energized. The correct relay is open on both terminals and then closes on both terminals when energized. Using the wrong 5 pin relay will probably run the car , but not run the 02 sensor heater.

My understanding is that the diodes in the relays prevent "flyback" through the switched circuit. Which is the current spike that happens when the field collapses in the relay. It prevents damage to sensitive circuitry in the computers generating the switch signals.

So is the fuel pump relay different from the main injection relay?

[DrewP]

In my cars I believe they are the same.