electrical and ignition Electrical in a 74'

[danielp.per3]

Hey fellow faq members i was hoping to get a second opinion on a electrical issue i am having with my automatic 74'. Around april my alternator and or regulator died on me so i decided to upgrade to a good used e21 alternator. After replacing the alternator and grounding cable i began to notice electrical issues... my guess was either a bad connection with the new cable or the internal voltage regulator but after replacing it today with a new one and not getting a result i am stumped..... any help would be appreciated.

 

thank you, 

Littleohtwo

[Simeon]

What are the electrical issues? (You got to give us something to work on)

[72_02]

Did the alternator just have 3 wires going onto it or the proper plug? Maybe they are mixed up. I think that can cause issues without knowing any other info. Check diagrams and look at the pin outs to the pin outs on the regulator.

 

Just a guess tho.

Edited September 8, 2016 by 72_02

[danielp.per3]

17 hours ago, Simeon said:

What are the electrical issues? (You got to give us something to work on)

Sorry about that a issue im having is the temp gauge bounces around and when i turn my lights on or press on the brakes the guage shoots all the way up, Another is when i pull the car out of park and into drive the lights dim and the gauge again shoots up...

[danielp.per3]

7 minutes ago, 72_02 said:

Did the alternator just have 3 wires going onto it or the proper plug? Maybe they are mixed up. I think that can cause issues without knowing any other info. Check diagrams and look at the pin outs to the pin outs on the regulator.

 

Just a guess tho.

it had two wires going into it... the battery cable and the (blue) one 

 

[7502]

I just installed a re manufactured e21 alternator last week, and it worked out well, no issues.  I simply ran a blue wire from the D+ on the alternator to the D+ terminal on the 3 way plug at the old unneeded voltage regulator. The rest of the set up is the same.  You might want to add proper grounds to the front parking/turn signal light assemblies as well.

['76mintgrün'02]

The instrument cluster sometimes has issues with being sufficiently grounded.

It sometimes helps to add a ground wire to these two brass nuts.

I simply made a copper tab to put under them and added a wire to it.

(and customized a crappy screwdriver to do the job)

(and added BMW, so it looks really extra super cool)

[danielp.per3]

53 minutes ago, 7502 said:

I just installed a re manufactured e21 alternator last week, and it worked out well, no issues.  I simply ran a blue wire from the D+ on the alternator to the D+ terminal on the 3 way plug at the old unneeded voltage regulator. The rest of the set up is the same.  You might want to add proper grounds to the front parking/turn signal light assemblies as well.

yea i followed the installation write up on the faq... the alt. seems to be functioning well and charging the battery and so an extra ground..? 

[danielp.per3]

27 minutes ago, '76Mintgrun'02 said:

The instrument cluster sometimes has issues with being sufficiently grounded.

It sometimes helps to add a ground wire to these two brass nuts.

I simply made a copper tab to put under them and added a wire to it.

(and customized a crappy screwdriver to do the job)

(and added BMW, so it looks really extra super cool)

thanks for the suggestion ill give it a try.. 

[Simeon]

Check your grounds carefully. There should be a thick wire between the alternator body and the engine. Engine to body (via a strap) and battery to body / engine also via a strap.  I would also look for bunches of brown wires around and underneath the battery where headlights and other grounds are screwed to the body. Check that these connections are good and are clean from corrosion. 

 

The additional ground connection at the instruments is a good one too.