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Discussion Starter · #1 ·
Hello All-
Quick question, as I have been searching the WIS and can’t seem to find the answer to my question about my 08 Saab Aero.
Trying to figure out where the two ground wires (I believe they are grounding wires) that are screwed to the case of the ECM. One wire is thinner than the other.

The reason this came up, I now have experienced this twice, codes of p1895,p1896, p0700 and p0101 being set. From what I read the cause of all these four codes occurring at the same time can be a grounding problem and/or a connection at the connectors under the battery tray. I started with checking the grounds at the ECM, and found the heavier wire bolt loose. Just trying to understand where these go and unable to find them in the WIS.
Thanks
stock, eBay photo to show the wires
 

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These are not grounds actually, these are static discharges as far as i remember, the ECU is grounded through its casing by means of contacting the engine, and the engine is grounded through a main cable to the chassis .
 

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Discussion Starter · #3 ·
Thanks for the information. The LH side looks to be what you say, maybe a shield for the cable.
The RH side, the thicker wire-black with a white stripe, looks to be a ground for something, this is the one that was loose. Next time I have the intake pipe off I will physical trace it.
So for now that wire is now grounded.
 

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These are not grounds actually, these are static discharges as far as i remember, the ECU is grounded through its casing by means of contacting the engine, and the engine is grounded through a main cable to the chassis .
Hi, I wanted to ask you about this post, do you still think these wires are static discharge, do you know where the other end of the black and white wire is? I noticed in a more recent post that you said they were grounds, we are trying to trace the ends of both of these wires to test for continuity and we have no idea where they come from.
Thanks
 

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Discussion Starter · #5 ·
Trying to remember, the thinner wire is a shield for one of the ECM cables.
The thicker one, the one you are asking about, is a ground. Now going by memory and I will double check when I get home. I believe it goes to a grounding point below the PS Reservoir (G7), which in return comes back up and run across the engine and goes down to the AC compressor. The grounding side of the ac coil.
Maybe I ask what’s is going on with the wire, I’m guessing you are OHM’ing it and it is not “grounded”? If so, give H7 connector a close look (disconnect and look at the pins). The grounding goes thru that connector. Don’t ask how I know.

Connector
283062
 

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Trying to remember, the thinner wire is a shield for one of the ECM cables.
The thicker one, the one you are asking about, is a ground. Now going by memory and I will double check when I get home. I believe it goes to a grounding point below the PS Reservoir (G7), which in return comes back up and run across the engine and goes down to the AC compressor. The grounding side of the ac coil.
Maybe I ask what’s is going on with the wire, I’m guessing you are OHM’ing it and it is not “grounded”? If so, give H7 connector a close look (disconnect and look at the pins). The grounding goes thru that connector. Don’t ask how I know.

Connector
View attachment 283062
Thanks! Let me know if you have more info, I'll put you on Christmas card list lol. It seems to go from the ECM, travelling in a direction towards the radiator and then disappears down at the front of the engine, it's hard to see without removing the radiator and stuff. This wire and where it goes is driving me mad, and the Wis is useless for wiring diagrams for this car. What was wrong with your car when the wire was loose? Phil
 

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Discussion Starter · #7 ·
Was having an issue when re-starting the car when it was warmed up.
What problem are you dealing with?
 

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Was having an issue when re-starting the car when it was warmed up.
What problem are you dealing with?
Same thing, it was a problem starting when warm, now it won't start or even crank at all. At one point, when it wasn't running, I thought I would fix that vacuum hose at the back and clean those grounds at the same time, when I touched the Black/White wire I thought I could sense voltage and when I put it back on the car, it started. After about 30 minutes running, it wouldn't start again, and hasn't since, I put it down to a coincidence until I read this post.
 

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Discussion Starter · #9 ·
Memory is shot. Got one wire figured out. The one that comes across the engine and disappears behind the turbo charge pipe, get bolted to the cylinder head.
More to come over the weekend.
I really don’t think this grounding wire(s) is your problem. But you have a good question on where they go, I’ll do my best to add more info.
283099
 

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The grounds are there to reduce electrical noise at the ECU. They will not cause a no start condition if they fail. They CAN cause rough running due to increased noise on the ECU inputs if they fail.
 

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To all, thanks for your help. I don't think this is my problem either. I was checking for a bad ground, and what I know about electricity, you could write in triplicate on the back of a postage stamp! But while I was waving my multi-meter around, hoping some magic would happen, and set on 20v DC voltage, I touched the engine block with the black lead and then touched that wire with the red lead, and got a reading fluctuating around 0.14, when I reversed the leads, I got the same reading with a minus. I am sure this can't be right, but I don't know why? Believing that wire to be source of the voltage, I have since disconnected it and checked; it has no voltage reading. If I touch the Red lead to the Ecm mounting bracket and black to engine block the reading is there. I will continue to pull my hair out, and buy a hat, they say electricity really exists but I've never seen it!
 

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Curious. Did you disconnect H7 and look at the pins?
Yeah I did, it looks like it is in good condition, if you need the EPC let know, I did notice in another post at one time you were looking for a part number. Thanks
 

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Discussion Starter · #14 ·
Thanks for the offer, I was able to get all the parts online.
Doesn't make sense why you are seeing a “voltage” between that wire and the engine block.
I would check the grounding point below the power steering Reservoir.
When I get more info on the path of the black/white wire I’ll update this thread.
As a side note, with your meter red lead on the positive of the battery and the black lead on engine block...what’s the voltage?
 

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Thanks for the offer, I was able to get all the parts online.
Doesn't make sense why you are seeing a “voltage” between that wire and the engine block.
I would check the grounding point below the power steering Reservoir.
When I get more info on the path of the black/white wire I’ll update this thread.
As a side note, with your meter red lead on the positive of the battery and the black lead on engine block...what’s the voltage?
I have since checked that wire, it's not the source of the voltage. Depending on the condition of the battery at the time, sometimes I have to recharge it after using the TECH2, but it is always good around 12.6v to 12.9v, and it holds the voltage even after sitting for days of no use, the battery is new and has been tested twice.
 

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Does this look like what you're seeing?
 

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Does this look like what you're seeing?
Thanks Okcrum, that's exactly what I am seeing, the picture that shows, UEC battery voltage *V UEC ignition voltage +15 * transport fuse *, I have taken a fusebox from a running car and put it in, but get the same result on the TECH2, it won't add and still says, UEC missing on bus and the voltage test still says UEC battery voltage *V, UEC ignition voltage +15 *, Transport fuse * Also tried bus reset didn't help. I have pinged all the modules for errors all good except UEC and REC
 

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Ya, can't add it if you can't talk to it. What else will make a UEC seem dead when it isn't? UEC communicates on I bus (single wire) so a bad connection or two can drop modules off the bus. No power would do the same. Beyond that the failures get dicier. Here's an I-bus diagram. OBD port goes to CIM which goes to UEC via MIU. Note that failure in H102-1 can disconnect both REC and UEC from I bus (EDIT: and a few other things).
Rectangle Font Line Screenshot Parallel
 
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