Jump to content
78LB620

1985 720 weird electrical gremlin all of a sudden

Recommended Posts

Hey guys, 

 

Wonder if anybody has seen this particular set of behaviors on a 720.    Friday night on the way home from work, I noticed the temp gauge was pegged at the top of the gauge.   Oh no! me thinks the water pump or something took a dump.    I pulled over and checked the radiator and everything seemed normal.   Continued down the road and noticed the fuel gauge was also pegged.   I know I had about 1/2 of a tank when I left work.   Strange.

 

Then a few blocks later I turned on the left turn signal, waiting to turn at a light and the right one turned on.   Switched over to the right and sure enough the left one started flashing.   I could see both blinker indicators flashing very dimly.    I worked the flashers on and off a couple of times and they didn't see to come on more than they were when off.

 

When I got home I messed with it for a few and discovered the gauges returned to normal after sitting at idle for a few minutes.    The flashers started working as expected too.

 

My first thought was the voltage regulator in the alternator, so today I swapped it out with a new one.    No Luck!   Same bahavior.

 

I read through everything on here I could find for similar behavior but nothing matched exactly.    Any ideas what  I should check next?

 

Thanks

Edited by 78LB620

Share this post


Link to post

Surprised nobody took a stab at this. First thing I do with weird 12 volt issues is clean every ground I can get to. Starting with the battery terminal, engine ground wire, body to engine wire, ect.

Share this post


Link to post

Must have missed this.

 

 

First thing is STOP REPLACING THINGS. Your alternator (that turns out is fine) is almost $400 from the dealer, and a better product than the $60 POS you replaced it with. These 'rebuilt' items are 50% bad in the box. So if you have the old one put it back on and take the other one back. If you turned it in there is a chance that you have added another problem.

 

Trouble shoot it and find what's wrong and replace it. Start with the above comment about cleaning the battery posts and camps.

Share this post


Link to post
On 11/27/2019 at 6:20 PM, datzenmike said:

Must have missed this.

 

 

First thing is STOP REPLACING THINGS. Your alternator (that turns out is fine) is almost $400 from the dealer, and a better product than the $60 POS you replaced it with. These 'rebuilt' items are 50% bad in the box. So if you have the old one put it back on and take the other one back. If you turned it in there is a chance that you have added another problem.

 

Trouble shoot it and find what's wrong and replace it. Start with the above comment about cleaning the battery posts and camps.

Thanks Mike,  I knew you were gonna let me have it for replacing the alt without any proof it was bad.   I felt like an idiot after I put the reman POS in there and it didn't change a thing. 

 

All the cables and grounds are clean and secure.    I pulled the guage cluster out and low and behold it was coated in gear oil.   The brand new speedo cable I installed is walking gear oil up into the cluster.    I thought the new cable would remedy this and it seemed to for about 1k miles, but obviously the cable wasn't the problem.   Is there a seal internal to the transfer case on the speedo drive that could have worn out?   I cleaned all the oil out of the cluster and connectors and everything functions as expected now.   I am just concerned that the speedo continues to spew.

Share this post


Link to post

Yup, there is a oil resistant seal.

 

115AcEe.jpg

 

 

dE70HSq.jpg

 

Maybe make something with a small hole and pull the cable all the way out from the cluster and slide it on from that end. I don't have a part number for it because it's part of the speedometer assembly.

 

If this doesn't help (it should if yours is missing or damaged) there is also a seal (the small one) around the spindle with the plastic gear on it. Knock the roll pin out and the spindle pulls out easily. I doubt Nissan would have one available but you can try.... 32709-14600 .... it's not an O ring but more like a sleeve.

 

Jo98aZl.jpg

Share this post


Link to post

I bet it is the one on the shaft.   Didn't think about that.   The original cable was missing the little top hat and was a bit chewed up on that end.   Now me thinks the inside of the drive assembly might have gotten buggered up at the same time.  Makes sense.

 

Thanks Mike, just reminds me to post first 🙂 you are the best!

 

Cheers

 

  • Like 1

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.