One of the items on the punch list for my ’87 E30 325is was fixing an intermittent problem in the power windows. The previous owner told me that the problem existed on both driver and passenger-side windows, and that he’d replaced both switches but the problem persisted. I lifted the switches and the sockets they plug into up out of their recesses in the trim piece surrounding the shifter, and wiggled wires around as I exercised the motors up and down. The problem did occur intermittently on both sides, which initially made me think that it was something systemic to do with window- power supply. But the failure definitely appeared to be correlated with movement of the wires going into the back of each connector, so the fact that both sides failed intermittently was most likely coincidental. 

    I could’ve used a multimeter to check voltage at the connector, but my gut told me that this was a problem with connector contact, not electrical supply. I gently pried open the back of one connector socket shell to see what was amiss.

    There are six wires that go into the back of the connector shell. Each wire has a crimped-on terminal that looks like a female spade connector, at a right angle to the wire. The terminals slide into individual channels in the back of the connector. There didn’t appear to be any barbed pins to lock them into their channels; they simply seemed to slide in and be held there by the snap-on back of the connector. 

    I put it all back together, slid the switch into the connector (which slides the six male spade terminals on the back of the switch into the six female spade terminals in the connector shell), and looked at it carefully. I noticed that the snap-on back of the connector bulged outward.

    Gotcha! It was likely that one or more of the prongs on the back of the switch wasn’t going into its corresponding terminal in the socket.

    I pried the connector back open, gently removed all six terminals, and inspected them closely. I found that two of them were mangled like this:

    You can see that these are, in fact, not standard female spade terminals; they’re “double-leaf spring contacts.” Each terminal has two spring-loaded contacts that press against each other. The male spade on the switch is supposed to slide between them like a butter knife between your thumb and forefinger. Instead, the male spade had mashed and mangled the contacts and was no longer sliding between them. That’s why the switch wouldn’t seat all the way, and that’s why the connection was intermittent.

    Below is a photo of a good (left) and a mangled (right) terminal side-by-side.

    I tried using a very small screwdriver to un-mangle it, to no avail.

    No problem, I thought. I’ll go on realoem.com, find the part number for the terminals, order a few of them, cut the bad ones off, and just crimp the new ones on.

    I searched on realoem and found double-leaf spring terminals listed as an E30 part (part number 61 13 1 370 692), but they were straight, not right-angle terminals, and straight ones won’t work because you wouldn’t be able to snap the back of the connector shell shut.

    Since I came up empty on realoem, I posted photos of the original terminal to Facebook and rv3limited.com, but no one could come up with a part number for these angled terminals. Some folks theorized that from a purchasing standpoint, the terminals might be integral with the connector shell and not available as a separate part. Someone suggested that I go to the electronic-component site mouser.com and try to find the terminals.

    I was about to do that when my Facebook friend Levent Erhamza of GutenParts.com messaged me, saying, “We have drawers full of short wires with these terminals from cars we’ve disassembled. Just let me know which colors you need and I’ll send them to you.” The only problem with taking Levent up on his kind and gracious offer was that I needed to disassemble both the left and right connectors and inspect all of the terminals to figure out which ones I needed.

    I hopped on eBay and found that there are vendors who sell the six-wire E30 and E28 power-window sockets for use with illuminated switches, with lengths of the six wires attached as pigtails for $15 a side. I thought, perfect, I can click and buy, and I won’t have to disassemble anything; I can just splice on the whole connector. I thanked Levent for his generosity and told him I’d take him up on it next time, but this time I was opting for the easy way out.

    I ordered the two pigtails. 

    When they arrived a few days later, I took them out to the garage and staged them on the passenger floor of the E30. I was thi-i-i-s close to simply cutting the existing units off the E30 and splicing these on when I thought, “No, slow down.” And it’s a good thing I did, too, because when I test-fit the window switches into the pigtails, the snap-on backs of the connector shells bulged in exactly the same way as the ones in my car. These pigtails, too, appeared to have mangled terminals that prevented the switches from seating completely.

    So I did what I should’ve done in the first place: I disassembled both connectors in the car, removed all twelve terminals, and inventoried exactly which ones were bent (two on each side). Then I disassembled both of the pigtails and noted which terminals were good. Fortunately, between the two pigtails I’d bought, I had enough wires and terminals to fix both sides using matching wire gauges (diameters) and colors. 

    Usually I’d solder and heat-shrink splices like this, but in the mess that is my garage, I couldn’t find my solder, so instead I crimped four butt-splice connectors, and put heat-shrink around the splices to provide a little extra protection.

    I inserted the switches into the sockets, and for the first time, they mated fully without causing the snap-on back of the connector shells to bulge. I tried the switches, and they rolled the windows up and down without fanfare. I moved the switches, sockets, and wires around, and could not make them fail. I slid the switches back down into the recesses in the shift-surround piece and verified functionality one final time. The problem was fixed.

    Man, you combine this with last week’s E9 taillight repair, and I am on a roll. Small electrical stuff is getting fixed. I could get used to this.—Rob Siegel

    Rob’s first book, Memoirs of a Hack Mechanic, and his new book, The Hack Mechanic Guide to European Automotive Electrical Systems, are available through Bentley Publishers, Amazon, ECS Tuning, and Bavarian Autosport—or you can get personally inscribed copies through Rob’s website: www.robsiegel.com.