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Username Post: 1954 Chevy Truck Electrical Mystery        (Topic#359444)
machtoo 
Newbie
Posts: 6

Reg: 01-11-20
01-11-20 01:01 PM - Post#2784192    

I own a 1954 Chevy Truck that was converted to 12V in an older restoration. The truck has been running quite fine and normally starts immediately. Here is my mystery...had a new clutch put in recently. Drove it home and parked in the garage. Noticed the brake light was not working so traced it to a disconnected wire under the dash. The running lights were not coming on so I traced it out with a meter and discovered the lights were wired but no voltage from the headlight switch, so made plans to see where the connection was bad. In the meantime, I ordered and replaced the 2 terminal strips on the inner fenders as the originals were loose on one end. Straightforward job to bolt them on and transfer the wires on lug at a time. Received a radio for the truck for Christmas and mounted it in the dash. Was planning to wire it to the ignition switch but when checking with the meter I could not find 12v. So started tracing. I checked the battery connection on the regulator on the firewall and only measures 3v. After removing the connected wires I reconnected one at a time. I connected the wire from the battery and measured 12v. Reconnected the next wire and still has 12V. Connected the wire from the alternator and the voltage dropped to 3V. This seemed unusual. With the alternator wire disconnected I measured 12V on the back of the headlight switch, however, nothing in the dash is working. No headlights, no gauge lights, no 12v to the coil ballast resistor. I tried to start the engine. Started turned the engine but no fire. I am an electrical engineer and have restored other vehicles but this one has me stumped at this point. I will check the battery voltage when turning on the headlights but if the battery is turning the starter I do not think it is the battery. Big mystery. Any ideas would be appreciated.



 


RAM_51 
"4th Year" Silver Supporting Member
Posts: 5548
RAM_51
Loc: Yakima, WA. USA
Reg: 12-28-02
01-11-20 03:07 PM - Post#2784201    
    In response to machtoo

A lot to digest there. If the starter was taken off for the clutch replacement...there could be a misadjustment on the starter button and switch if your truck is still so equipped. Another thing to look at would be the headlight switch itself for the running light issue.

1951 Fleetline Preservation
'51 Fleetline DeLuxe 2 DOOR SEDAN (Fathom Green)
'51 Styleline Special BUSINESS COUPE (Shadow Gray)
'53 6500 Dump Bed (Oxidized Red)
'50 Styleline DeLuxe 4 DOOR SEDAN (Mist Green)


 
machtoo 
Newbie
Posts: 6

Reg: 01-11-20
01-11-20 03:34 PM - Post#2784204    
    In response to RAM_51

Thanks for the response...the interesting thing is everything worked fine driving it home from the clutch work.



 
RAM_51 
"4th Year" Silver Supporting Member
Posts: 5548
RAM_51
Loc: Yakima, WA. USA
Reg: 12-28-02
01-11-20 08:12 PM - Post#2784218    
    In response to machtoo

Could also be a loose wire...or one that has a little corrosion on it. I did drop the starter on my '53 6500 to replace the drive. I now have to be careful to not push the floor start too deep as it will disconnect power to the engine. If I do, the starter will spin just fine, but the engine will only "light" when the plunger is coming back up. This never happened before I dropped the starter so there is obviously something out of adjustment. I'll get to it eventually. For now, I just have to remember where the sweet spot is.

1951 Fleetline Preservation
'51 Fleetline DeLuxe 2 DOOR SEDAN (Fathom Green)
'51 Styleline Special BUSINESS COUPE (Shadow Gray)
'53 6500 Dump Bed (Oxidized Red)
'50 Styleline DeLuxe 4 DOOR SEDAN (Mist Green)


 
rrausch 
"16th Year" Silver Supporting Member
Posts: 14189
rrausch
Loc: L.A, Cal. & St. Louis...
Reg: 04-07-03
01-11-20 08:46 PM - Post#2784219    
    In response to RAM_51

I had two '54 trucks--a half ton and a 3/4 ton. Loved 'em both. The 3/4 ton was subject to electrical goblins also.

I agree, your post is a lot to digest.

'54 Chevy radios are rare beasts. Whoever gave you one for Christmas must like you a lot. Have you ever seen the optional clock for the '54? Both my trucks had the clocks. Unfortunately my first '54 was stolen in 1992, and I never saw it again.

1953 210 Convertible, 261 with dual Carter YF 966S carbs, P.S., Remote Bendix P.B. Booster... shade-tree restoration about done.




 
50hotrod 
"8th Year" Silver Supporting Member
Posts: 1042
50hotrod
Loc: Wisconsin
Reg: 07-25-11
01-12-20 03:53 AM - Post#2784225    
    In response to machtoo

Clutch replacement now electrical problems.

The first thing that comes to mind would be a ground strap or ground wire that was connected to a bell housing or starter bolt from the body of the truck. Check the body ground.

1950 CHEVY 2 DOOR 327 TRI POWER FENDERWELL HEADERS HEIDT FRONT SUSPENSION 700R4 TRANS 411 REAR



 
machtoo 
Newbie
Posts: 6

Reg: 01-11-20
01-12-20 01:01 PM - Post#2784261    
    In response to 50hotrod

Well after hours of tracing voltages and wiring, everything seems to be pointing to a failed ammeter even though it is only 6 months old. I know 12v is going from the starter switch to the input side of the ammeter which is correct according to the wiring diagrams. Since all discharge flows through the ammeter and nothing is powering up I think it has to be the ammeter gauge. I can remove the connections from the lugs and bolt them together and see if things work properly. Haven't been able to find any info on what resistance measurements across the gauge itself should be. Another day for that test.



 
machtoo 
Newbie
Posts: 6

Reg: 01-11-20
01-13-20 09:41 AM - Post#2784317    
    In response to machtoo

Well, mystery solved. As I went through all kinds of checks...grounds, continuity, etc I decided to test the horn relay manually with a jumper to 12v since the horn button was activating. First touch nothing...two more touches and it worked. The horn relay was stuck and apparently draining all power past the ammeter. Ordered a new horn relay.



 
RAM_51 
"4th Year" Silver Supporting Member
Posts: 5548
RAM_51
Loc: Yakima, WA. USA
Reg: 12-28-02
01-13-20 10:28 AM - Post#2784321    
    In response to machtoo



1951 Fleetline Preservation
'51 Fleetline DeLuxe 2 DOOR SEDAN (Fathom Green)
'51 Styleline Special BUSINESS COUPE (Shadow Gray)
'53 6500 Dump Bed (Oxidized Red)
'50 Styleline DeLuxe 4 DOOR SEDAN (Mist Green)


 
machtoo 
Newbie
Posts: 6

Reg: 01-11-20
01-13-20 11:31 AM - Post#2784329    
    In response to RAM_51

Well, jumped for joy too soon. Everything was working beautifully checked the lights...OK...tried the turn signals...a blink and then dead again...nothing working...back to the drawing board...I know the first thought is a bad ground but I have checked grounds to the other side of the truck for continuity with a long jumper to the battery negative cable..all checked out fine...essentially perfect.



 
eplantage 
Frequent Contributor
Posts: 2271

Loc: Southern MN
Reg: 03-15-04
01-13-20 12:44 PM - Post#2784334    
    In response to machtoo

I would check the dimmer switch too.

Age: 66 at the moment
1950 Chevrolet Sedan Delivery
1953 BelAir Convertible Project
2002 Heritage Springer FLSTSI
1930 Model A Standard Coupe


 
dsacton 
"3rd Year" Silver Supporting Member
Posts: 1211
dsacton
Loc: Boulder, CO
Reg: 11-01-11
01-14-20 02:22 PM - Post#2784392    
    In response to machtoo

As I recall, there is a bimetallic thermal "fuse" on the headlight switch. Could this be bad or intermittent? I may be remembering this totally wrong.

Scott Acton
1954 Chevy Bel Air 2-door
http://www.my54chevy.com


 
RAM_51 
"4th Year" Silver Supporting Member
Posts: 5548
RAM_51
Loc: Yakima, WA. USA
Reg: 12-28-02
01-14-20 02:29 PM - Post#2784393    
    In response to dsacton

  • dsacton Said:
there is a bimetallic thermal "fuse" on the headlight switch.


You are absolutely correct!


1951 Fleetline Preservation
'51 Fleetline DeLuxe 2 DOOR SEDAN (Fathom Green)
'51 Styleline Special BUSINESS COUPE (Shadow Gray)
'53 6500 Dump Bed (Oxidized Red)
'50 Styleline DeLuxe 4 DOOR SEDAN (Mist Green)


 
machtoo 
Newbie
Posts: 6

Reg: 01-11-20
01-16-20 12:51 PM - Post#2784485    
    In response to RAM_51

Many hours of testing and after 4 days everything seemed to lead back to the ammeter gauge. I bit the bullet and un-bolted the gauge cluster to get easier access to the gauge and connections. First step...measured voltage...battery side was 12...other side was 1 v. Second step...removed the two wires and connected them together...measured 12v everywhere expected...so there was a massive drop across the gauge. Third step...removed the gauge from the cluster and checked continuity...essentially an open circuit. Checked my old gauge which was still working when removed...show zero ohms as expected since the gauge is basically a shunt/straight connection. So, we have an almost new gauge that is bad and has a very intermittent connection internally. Replacement is coming from the supplier after a call. What a challenge...decided to also replace the two major ground straps and adding 5 or 6 smaller straps at various location including adding one from alternator to frame.



 
RAM_51 
"4th Year" Silver Supporting Member
Posts: 5548
RAM_51
Loc: Yakima, WA. USA
Reg: 12-28-02
01-17-20 07:41 AM - Post#2784524    
    In response to machtoo

  • machtoo Said:
What a challenge


If the '54 BATT, TEMP, OIL, FUEL cluster is anything like the '47-'53 [slight design change] it is a real bear to get out of the dash. I found it easier to remove the speaker grille and speedometer and work through those openings to get to it. That, or remove the clutch and brake pedals if working from under the dash. Either way, it is not a fun task!


1951 Fleetline Preservation
'51 Fleetline DeLuxe 2 DOOR SEDAN (Fathom Green)
'51 Styleline Special BUSINESS COUPE (Shadow Gray)
'53 6500 Dump Bed (Oxidized Red)
'50 Styleline DeLuxe 4 DOOR SEDAN (Mist Green)


 
Ray P W 
Contributor
Posts: 471

Reg: 09-30-15
01-17-20 01:58 PM - Post#2784550    
    In response to RAM_51

"So, we have an almost new gauge that is bad and has a very intermittent connection internally. Replacement is coming from the supplier after a call."

Machtoo,

Would you be willing to tell us what vendor sold you that gauge? I wouldn't be surprised if it is from China.

One of my sons is an electrical engineer and the other is a mechanical engineer. I'm an engineering geologist so between the 3 of us we can tackle a variety of projects.

Imagine how challenging it would have been to find that ammeter defect if you weren't an electrical engineer. Good job!

Ray W



 
rrausch 
"16th Year" Silver Supporting Member
Posts: 14189
rrausch
Loc: L.A, Cal. & St. Louis...
Reg: 04-07-03
01-18-20 08:26 PM - Post#2784624    
    In response to Ray P W

Wow. Good job tracking down the culprit.

By the way, school buses and 1.5 and 2 ton trucks in '55-'56-'57 had '54 gauge clusters in them, AND the gas and temp gauges were 12V.

1953 210 Convertible, 261 with dual Carter YF 966S carbs, P.S., Remote Bendix P.B. Booster... shade-tree restoration about done.




 


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