I am sorry but I don’t understand you. If the module harnesses are just swapped, no reason to expect “burning”.
Both have WP and B - power and ground. If those are on the correct pins, then everything else can be checked with a multimeter.
I provided the electric diagram already, here is the explanation. Ohm the U and R wires from the B-bank module to pins 9 and 10 at the Marelli ECU (passenger footwell). Same for the N and G from the A-bank module to pins 14 and 15 and you’ll know!!
Thank you for providing the diagram Steve but I already had it and was studying it. I realize the positioning of the modules mean nothing as far as operation goes but it is indicative of alteration. The module harnesses are not just swapped, they have the wiring bastardized differently on each one yet the car ran. There is more than one way to skin a cat but both of these look wrong.
Thank you for using the word shielding as it got me thinking in a different direction. I rechecked the jumper wires from blue and red to the black ground wire. Using magnifying glasses to aid my 61 year old eyes I now see the jumper wire is soldered onto the shielding around the power module outputs.
The shielding was not pulled back over the outer insulation and soldered there. It was soldered right over the the blue and red wires. Was not expecting that and assumed the red and blue wires were simply soldered together with the black ground wire.
There is a momentary continuity between the red wire and the ground wire, then infinity on all scales. Not so on the blue, not so on the brown and green on A module. I have my direction. Thanks for your help.
You’re welcome.
Worst case scenario - you’ll have to redo the wiring from end to end yourself.
Not too bad - just a handful of wires. Connectors obviously can be reused.
Good luck!
That’s what I would do. Remove all uncertainty, and get to what should be a “known good” set up. I’ve recently remade and extended some of the wiring in my engine bay, and have used woven plastic sheath to good effect, rather than wrapping with tape.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
65
That is so weird. Ya gotta wonder what somebody was doing in there and why they decided to stray from the original wiring setup and create something of their own invention.
It may have been you that said to ground that shielded cable on only one end, read it going thru forum searches. Big picture is I knew it was a mess when purchased.
Paint is nice, Flamenco Red, interior solid 8/10. Engine quiet, no cam chain rattle on decel when revving, 106K. Tracks straight, trans shifts nice, no slip, top good shape. Changed hands 3 times in less than two years. Sold for $10K in Seattle. I bought it for $4500 in San Antonio. Less than 300 miles put on it since the three sales.
Looks like a nice alloy radiator. Could be that this electrical gremlin was intermittent and drove the bodgers crazy. It finally gave up the ghost for me. Over the years have seen infinite resistance on many things until they get current, usually underground low voltage applications. The the wires just barely touching, often corroded, will conduct current.
You folks may have just helped me solve a mystery that frustrated three previous owners. Thank you all. Will probably have at it next weekend after this storm is out of Texas.
The wiring to B module may have been intermittent for some time. The A module appears to have been replaced recently with a correct Marelli part number, and the ground to the shielding has been cut. Did it short out and they simply cut the ground?
It is difficult for me to think in terms such ignorance and and poor workmanship but it looks like I will have to to sort things out.
As soon as it runs on both banks the wiring is getting redone. Who knows what has been done just waiting to fail. To me the car is not roadworthy until that is done. The woven plastic sheath was used on Honda motorcycles in the '80s, very tidy. The plastic sheath motorcycle manufacturers used would get very hard and brittle in less than ten years.
