Starter Not Disengage 1997 850 T5 RESOLVED, wiring wrong

Post by **abscate** » 11 Jul 2013, 15:35

please confirm success after you have rewired so we can close thread

drzaeis · Post by **drzaeis** » 11 Jul 2013, 18:55

Great success...it was wired incorrectly, both leads go on the outboard stud...not going to use that mechanic again. he swears the two big wires were on separate terminals when it came off..

Post by **abscate** » 11 Jul 2013, 19:25

he swears the two big wires were on separate terminals when it came off..

He can swear all he wants. They weren't. With your nice pictures documenting the mistake, I would nicely ask him if you should expect any further electrical damage as a consequence and how should you proceed if that happens?

Then forget about it and move forward.

Post by **cn90** » 11 Jul 2013, 20:52

drzaeis wrote:Great success...it was wired incorrectly, both leads go on the outboard stud...

I understand that you fixed the problem, but could you post an updated photo, take a few photos and post them, as I am curious how you did it!

Now I am confused...

- On the outboard stud, as jimmy57 said, there is supposed to be RED cable only.
- If you attach the BROWN Cable (supposed to be some kind of ground) to the outboard, you will probably short the battery?
- See the photo below:
* 1st image is yours, even though the BROWN wire is not supposed to be there, it is ground anyway.
* 2nd image is the factory setup with ground strap btw solenoid and starter motor.
* 3rd image is the Volvo 850 Starter circuit.

Maybe some gurus can explain the mystery?

YELLOW #1 is ground, #2 is the green wire (which is controlled by the ignition switch), #3 is the RED Cable (always hot).

: starter1.JPG (90.99 KiB) Viewed 1139 times

Post by **jimmy57** » 11 Jul 2013, 23:21

The bare wire out of starter case is not a ground, it is the + wire to the pair of + brushes, the ground brushes are connected internally to the motor case to be grounded. Look at the black rubber cone shaped grommet where the braided lead enters motor case in the photo. A ground lead would need no insulation from the motor case. If you survey a number of different makes of starters you will find that lead bare like that. My two John Deeres, my two Ford diesel PU's, and the Komatsu dozer I rented all have bare braided or a solid copper strip that goes from switched solenoid main terminal into motor case.
Color codes are not stringently adhered to and some insulation stains or gets color bleed. I think the alt to battery cable post at starter on my 98 XC70 was brown.

Post by **BEJinFbk** » 12 Jul 2013, 01:19

A picture really is worth a thousand words.
I never would have guessed this one...

Glad you got it fixed.

Post by **abscate** » 12 Jul 2013, 03:40

When someone wires incorrectly it gets ugly real fast, especially unfused battery cables .

I can almost sense the really knowledgeable people here cringe when we get a " I have electrical problems" and then post a picture of some totally Charlie Foxtrot wiring job

Post by **cn90** » 12 Jul 2013, 08:06

This is strictly for academic discussion.....the normal process is:

1. Crank the starter, current flows to GREEN wire, activating the Solenoid.

2. The Solenoid is moved (BLUE arrows), and 2 things happen simutaneously:
- engaging the clutch to flywheel
- sending power to the motor (RED arrow current flows from "2" to "3")

* Even with the 1st photo posted by the original poster... The BROWN Cable (which I assume is ground) is a mystery. I have never seen the big Brown cable in the vicinity of the starter motor.

* Now if the BROWN Cable was attached to the inboard post, why didn't he see sparks flying when he cranked the starter?

: starter.JPG (50.06 KiB) Viewed 1066 times

Post by **abscate** » 12 Jul 2013, 08:13

You cant use colour coding to ascertain wiring function reliably, especially on big cables which have likely been replaced. It looks to me like Volvo chooses to make the main primary connection from the alternator output by mating this cable to the battery cable connection at the starter, which makes sense.

Brown does not mean ground in this case, but perhaps the only colour cable the shop had with the previous owner replaced the cable..

Post by **jimmy57** » 12 Jul 2013, 08:24

Volvo and other manufacturers do not adhere to red=positive, brown or black=negative. Volvo used blue ground cables for years. Wires in a multi lead harness need color code. Large cables with lugs that fit onto posts and run by themselves or in a sleeve with only a few wires do not need color coding. That alternator to starter 50 stud cable is no more than 18 inches, probably 12-14 inches long. No need to worry about color when it will need no tracing by color in manufacturer or normal service.

Starter Not Disengage 1997 850 T5 RESOLVED, wiring wrong

Re: Starter Will not Disengage 1997 850 T5