Backup Lights and Speedometer Put Up a Fight

By: Bob Goodson

April 26, 2020

So far, I’ve been able to sort things out and get the exact result I wanted. This post covers two things that HAVEN’T worked out the way I’d like.

The speedometer in the car wasn’t working properly from the first test drive. I knew I’d have to tend to that. The needle would register speed, but clearly it was reading way too low. Additionally, the needle wouldn’t return to zero when I stopped. Often it wouldn’t register when I slowed down — acting more like a tach “tell tale”. The odometer, on the other hand, seems to be working fine. Doing a little testing I discovered that the odometer is reading way too fast — that is, when I cover an actual 15 miles, the odometer reads about 21 miles. Because it was inexpensive, I bought a new cable/housing from Rock Auto. Figured it couldn’t hurt. Unfortunately, the cheap price was reflective of the quality. As you can see in the picture, the new cable was too short for the housing – at the bottom of the picture you can see how little the cable protrudes from the housing – it won’t engage the speedometer. So it was a return. Interestingly, Rock Auto credited me and then said “don’t bother sending it back”.

So, I removed the cable from the stock housing and cleaned/lubed it. Had it spinning on a drill like butter. Unfortunately, that didn’t solve the problem — the speedometer itself is malfunctioning and the odometer is inaccurate. So I’ll either pull it out and send it off to be repaired or install an aftermarket GPS powered speedometer. Decision later.

The car also didn’t have functioning backup lights. Turns out the backup light switch had the electrical connection bits broken completely off.

Rock Auto to the rescue. However — before I installed the new switch I tested it to be sure it was closing properly. No problems, worked just as it should. So I installed it in the tranny. And I discovered that when I put the transmission in reverse, the tranny wasn’t activating the switch. That’s an internal transmission issue. Since the tranny is otherwise working beautifully, I decided to simply wire the reverse lights through a switch. Schematic told me that if I tapped into the red wire/blue stripe in the trunk and the blue wire/red stripe at the fuse box and connected all that with a new wire – I’d have backup lights. Put a little illuminated-when-closed switch right by the hood release handle to the left of the steering column.