Hitman's Pontiac Trans Am Forum

Trans Am Information => Trans Am Tech => Electrical => Topic started by: 1980MNT/A on September 17, 2009, 09:18:39 PM

Title: Choke Heater Relay...
Post by: 1980MNT/A on September 17, 2009, 09:18:39 PM
Hello everyone!

I have an annoying problem that has been going on since I bought my car last year.  When sitting at an idle or coasting (minimal throttle application) while driving the Choke Heater Relay buzzes slightly.  However, during moderate or higher throttle application, the buzzing goes away.  When driving at night, the "CHOKE" light faintly illuminates with with the buzzing of the relay.  Also, every now and then when I start the car, the CHOKE light stays on until I hit the throttle and rev the motor a bit.  The owner's manual states that "the CHOKE light will appear until the engine is running and if the light does not go out after the engine is running, a generator circuit problem is indicated."

I did some searching on this issue and found the following post:


The post mentions that the problem might be releated to low voltage, however my voltmeter shows about 14 or 15 most of the time.  In this post, there is another link to a Performance Years forum post which tells how to bypass this relay when not using the original carb/choke set up.

I guess I don't know where to start on fixing this issue.  I know basic electrical work and can follow directions very well, but I don't know if I should just replace the relay (my Pontiac dealer has one in stock) or if it could be something else?

Has anyone else ever had this problem or have any ideas on how to fix it?

Thank you in advance for any and all help!

Title: Re: Choke Heater Relay...
Post by: jphillips3333 on September 18, 2009, 06:22:55 PM
Choke?  Heater?  Foreign to me in Florida, sorry. 

Sounds like you want to chase down the wiring schematic for you the year of your car as a starting point ... someone will probably be along that's had this same issue.
Title: Re: Choke Heater Relay...
Post by: 1980MNT/A on April 26, 2011, 03:52:19 AM
Well, I am bringing this almost two year old post back!

I FINALLY got around to doing some work on this issue.  I replaced the Choke Heater Relay with a new one.....and it didn't help.

So, I am back to square one.  I think the next step is to trace all the wiring back looking for shorts and loose connections.

Any other ideas?

Thanks in advance for any help!
Title: Re: Choke Heater Relay...
Post by: 80 4mula on May 25, 2013, 01:04:36 AM
I recently had the same issue.  Buzzing of the relay under the dash. I removed the relay and now the choke light stays on and the voltage meter fluctuates. I was told that the relay is bad but the issue is the alternator. Evidently, the diodes in the alternator fail causing the relay to fail. My choke pull-off is the original one so I'm going to replace the choke pull-off, the alternator and the relay. I'm a basic shade tree mechanic and not that great at electrical but this made a lot of sense to me. BTW the diodes can be replaced in the alternator but it's nearly as much as the alternator. This entire fix is about $85. $49 for the alt, $20 for the choke-pull-off and $14 for the relay. Obviously, I'm not the 1st one with this issue. Has anyone else tried this fix?

Title: Re: Choke Heater Relay...
Post by: 1980MNT/A on June 16, 2014, 03:52:13 PM
Hey guys,

I know I haven't been super active on the forum in recent years, and this post is super old, but I figured a reply was necessary!

I finally fixed this problem!  Since most forums serve as a make shift repair refrence book, I figured since I finally fixed this problem, I should post the solution as well!

Now, to be honest, after some quick checking of the wiring, I pretty much just lived with the buzzing noise and always figured I would put it on my list of things to fix later.  My Dad and I were talking about it and he did some internet searching and found the following post on Hot Rodders:


This pretty much describes the exact issue and mentions the alternator diodes (same as "80 4mula" did in a reply to my original post).  The members on the forum also go into the reasons why it was making the buzzing noise and how to fix it! 

I did some checking and I still have the original GM alternator in my T/A:


My alternator is a 70A model, which matches my build sheets and window stickers.  The diode pack that I needed was in stock at my local Napa warehouse for $3.53.  It's not a very big part!


We went and picked the part up and started in on the alternator.  Once we got the alternator out of the car, we split the case and seperated the halves (remember to stick a paper clip or small wire in the brush retaining hole on the side of the case, so when you split the halves, they dont go all over the place, ask me how I know  :) )


The diode pack is located on the heat sync at the bottom of the case.


Installation is reverse of removal. 

Once I got the alternator put back together, we put it in the car and started it up.....NO MORE BUZZING NOISE!!  You have no idea how the driving expirience of this car has improved with that annoying buzzing finally gone for good! 

All said and done, including getting the part, this entire fix took 90 minutes!  I can't beleive I didn't put more effort into getting this fixed years ago!

I hope at least someone will benefit from me posting the fix to this problem, but if not, it was worth it just to share in the joy I am having driving around a non-buzzing Trans Am!!!