juniper Posted November 1, 2017 Report Share Posted November 1, 2017 Hello I'm new! Just got a 1978 620. First car I've ever owned and first manual. Everyone I've talked to thinks I'm stupid for getting a car this old. But I love it. I am excited to learn everything about this machine. I'll provide pics soon! She runs great but there are a couple electrical problems. Most pressing: no dash/tail lights. I have read all the posts about this problem but none of the fixes have worked for me yet. I have deep cleaned the fuse box as well as the headlight switch. Everytime I put a new fuse in, it blows. I can't find any bare wires touching metal, and i jumped the dimmer switch wires because I thought that might be the issue. After working on it all day, I turn it on and the temp and fuel gauges dont work! My lack knowledge is starting to get frustrating! Any help is greatly appreciated! Thanks! 1 Quote Link to comment
datzenmike Posted November 1, 2017 Report Share Posted November 1, 2017 Does your charge light, brake light, oil light come on with the key? If yes then the fuse for these and the Gas/Temp gauge is good. If they do not come on then the fuse on the lower left is not working even though it may look OK. Try holding a quarter across the fuse clips. If the lights come on with the ignition key turned to on they the fuse was no good. If the fuse for running and dash lights blows it's just doing it's job. However it would seem there must be something touching ground to cause this. Look and see if someone has spliced a trailer towing plug into the wiring around the tail lights. It's almost always terribly done and wrapped with electrical tape. Salt water spray gets in there are corrodes the connections. If not... If you look behind the right rear tail light there is a 6 wire plug joining the main chassis harness to the tail light harness running across the back. Unplug this and try another fuse. If it stops blowing then the problem is in the tail light harness or the rear lights. If it still blows the fuse, look under the passenger side seat for the 10 pin connector and unplug it. If this fixes the blowing fuse then it's in the chassis harness under the truck. If it still blows it's in the cab between the floor and the dash or out to the parking lamps in the front. The engine lamp under the hood is also on this fuse. Unplug the dash light dimmer and see if this stops the fuse blowing. And for now welcome to Ratsun. 3 Quote Link to comment
flatcat19 Posted November 1, 2017 Report Share Posted November 1, 2017 You obviously need to start talking to cooler people. 1 Quote Link to comment
juniper Posted November 1, 2017 Author Report Share Posted November 1, 2017 damn! Thanks for the quick and thorough response. I'll try all this tomorrow and see what I can figure out 1 Quote Link to comment
juniper Posted November 1, 2017 Author Report Share Posted November 1, 2017 Fixed the gauges! Just a loose connection I think. I tried everything you suggested and the fuse still blows. I even disconnected the engine light. I have found these two spots where it looks like the grounds are disconnected. I also know that the hi beams don't work. could my problems be related/where should these wires connect too? fist pic is under hood, second is under passenger seat. 1 Quote Link to comment
Roadster-ka Posted November 1, 2017 Report Share Posted November 1, 2017 Unplug rear wire harness to diagnose. If fuse doesn't blow you know where to look. Mike was correct, trailer wiring if present, is the usual culprit. 1 Quote Link to comment
Cheetahking Posted November 1, 2017 Report Share Posted November 1, 2017 Hey - not going to chime in on the wiring - but it IS COOL to drive a car that old. You will do well to understand a more basic car like this, and learn to work on it, rather than become one of those people that doesn't know how to do anything for themselves. Well done! 1 Quote Link to comment
datzenmike Posted November 2, 2017 Report Share Posted November 2, 2017 Up in the upper right corner of the cab behind the glove box are several plugs going through the body into the engine compartment. A 12 and a 10 pin connector. Unplug the 10 pin connector and this disconnects all the front parking and side marker lights.and hood lamp. If it still blows then the problem is in the cab. Hopefully it a pinched wire on a parking light or something simple. 1 Quote Link to comment
juniper Posted November 2, 2017 Author Report Share Posted November 2, 2017 still blows. I found a blown 15a fuse behind the dash as well. is that related? 1 Quote Link to comment
datzenmike Posted November 2, 2017 Report Share Posted November 2, 2017 An in line fuse??? That would be for the cigar lighter and the room lamp. Still blows then the problem is in the cab. Did you disconnect (unplug) the adjustable dash light dimmer switch? 1 Quote Link to comment
juniper Posted November 2, 2017 Author Report Share Posted November 2, 2017 aha! yep, the dimmer is disconnected. what would the next steps be? taking out the instrument panel? 1 Quote Link to comment
datzenmike Posted November 2, 2017 Report Share Posted November 2, 2017 Or reach up behind and unplug the gauge cluster. Do you have a tach or any add on gauges like oil pressure? CD player? 1 Quote Link to comment
juniper Posted November 2, 2017 Author Report Share Posted November 2, 2017 yes, I have a tach as well as a cd player the previous owner wired in 1 Quote Link to comment
datzenmike Posted November 2, 2017 Report Share Posted November 2, 2017 I should have asked sooner. Unwire them or check what they did. This is just like the trailer wiring. Chances are that they probably wired them alright. Can't see them driving around without marker lights for long.... but their wiring skills may be poor and something is now not right. 1 Quote Link to comment
juniper Posted November 2, 2017 Author Report Share Posted November 2, 2017 wow! what a huge relief! It was the stereo! I unplugged all the connections and i have all the lights i was missing. Looks like one of the wires had a terrible splice. But now I can drive at night, I can figure out the stereo later. Thanks so much for the help!! 1 Quote Link to comment
datzenmike Posted November 2, 2017 Report Share Posted November 2, 2017 :thumbup: 1 Quote Link to comment
distributorguy Posted November 3, 2017 Report Share Posted November 3, 2017 Never could have guessed that outcome! Cool :thumbup: 1 Quote Link to comment
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