hi All --

Following on to post:
http://www.brickboard.com/RWD/index.htm?id=927963

Have encountered problem as described by my mech buddy below.

Anyone know which pins to reverse / splice / jump?

Thx!

- K
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The 83 and 84 brains (control units) are similar but not the same, and seem to work differently in a few ways. Their harnesses are different as well and are not plug compatible direct replacements.

Problem: Using the 84 harness,

1) We have no 12V to the + (15) terminal of the coil.
2) We don't know which connector (wire) to use from coil to injectors.

We verified that the grey terminal does connect to the ignition module and does pulse the coil on the - terminal (1) of the coil.

We're able to fire up the car by jumper-ing 12V to the + terminal (15) of the coil and sqirting starter fluid into the intake manifold. So... I don't think we have problems with the ignition harness.

The 83 12V to coil comes from ignition switch to starter to coil. 84 (brown wire designated for the + (15) terminal of coil) 12V comes from ...??? When cranking the engine, the brown wire also pulses ... need to find out where it comes from and/or where it goes.

The mystery orange connector connects into the 'Y' black connector with an orange wire that goes to the throttle position sensor. This orange tps line is traced back to the ingintion module - which is correct.

Next step, find out the difference between the 83 and the 84 brain (control unit pin out's on their connectors) and their harnesses. Once we understand that, we can modify (cut and jumper or run our own wires) the 84 harness to work like the 83.

Hey Kevin,

I have been keeping track of the situation and I agree with Art. The numbers given from ALLDATA are those of the Ignition Wiring Harness. That harness is different from the FI Harness. There is a very big chance that the ignition harness suffered more damage (being that it is already crumbling) when the Fuel Injection Harness was installed. I do not think the auto shop could of done anything about the ignition harness when they did the install since the rot is so bad that the insulation crumbles between your fingers. I would look into getting the replacement harness offered by the brickboard member on the previous post before making and wiring/splicing changes to the Fuel Injection Harness being that it is the right harness for the 83-84 model year. I know it must be frustrating not having your baby up and running after getting that replacement harness but it sounds like your almost finished with the repairs. Replacing the Igniton Wiring Harness will take the problem out of the equation and allow you to further diagnose any remaining problem with no worries about harness rot. It feels to me like you are almost there, keep me posted. Good Luck!

Sincerely,
--
Julio Meza

1979 264GL B27F 127K --> BW55->M46, CLS, IPD Sway, 81+ Dash, Gauges, Flat Hood & E-Codes

1979 262C B27F 163K --> Restoration Project

1984 245DL 216K --> Sport Wagon

2002 Mercedes C320S 33K --> Wifemobile

Sorry Kevin,

You speak of "brain" and "harness" and my mind translates fuel ecu and fuel injection harness - the one that suffers from rot and needs to be run under the intake manifold.

You give Alldata references to volvo ignition harness part numbers.

Alldata is a Chilton's outfit, right?
--
Art Benstein near Baltimore

Source of confusion -- we all know the harnesses are "supposed" to be the same... but according to Alldata (and what we seem to be seeing in person), they're different. (Sorry, can't figure out how to post that online)

Also, according to Volvo bulletin in Alldata - re harness replacement, it gives the following:

1980-1983 use part # 3515722-1
1984 for old part # 1346259-3 use part # 3515723-9 for coil on left side
1984 for old part # 1347847-4 use part # 3515885-6 for coil on right side

So we're all scratching our heads on this.

Anyone hit this issue before?

hi there, you might want to check out dave bartons website. alot of info on harnesses. http://personal.linkline.com/dbarton/WireHarnesses.html

My understanding is the same as rhaire's. The only diff is your replacement fuel injection harness has the socket to provide 12V to the heated sensor added in late '84. The 503 and 510 ECU is interchangeable, and to my knowledge, the only change made with the 510 is associated with quicker sensor warmup -- definitely not a pin compatibility issue.

Sounds like something broke in the replacement work.
--
Art Benstein near Baltimore

I do not believe there are any differences between the 83 and 84 B23 LH2 systems. I KNOW the ECUs are identical in application, at least the North American ones are, in terms if polug and go capability. Something is wrong with the evaluation, I think.