Click on image for the lowdown. 
====
| | |
8 members (Wally / Montana, Otto Skorzeny, TUTS 59, Jon G, JW51, 3800GUY, cmayna, 52GMC35424JD),
107
guests, and
4
robots. | | Key: Admin,
Global Mod,
Mod | | | Forums66 Topics128,065 Posts1,055,865 Members48,428 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Jul 2017 Posts: 13 New Guy | | New Guy Joined: Jul 2017 Posts: 13 | I have a 56 GMC 100 which I am rewiring and have a question for all about an abbreviation found on the wire for the temperature sending unit mounted on the engine block. The schematic shows "18 F - (H.W.)" for the wire going from the engine mounted sending unit to the temperature gauge.
Does anyone have an idea what "H.W." stands for? It is the only wire on the schematic with that abbreviation.
| | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy Chuck M, I assume you are installing an aftermarket wiring harness, I'll take a wild [censored] guess, Hot Water, or Hot Wire, or Heat Wire??? | | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 | 18 F is 18 gauge wire, F= Dark Green. The 18-F is shown on the official 55-59 GMC manual schematic. H.W. is not.
What schematic are you looking at?
If it is a aftermarket harness, assume it is harness company nomenclature. Call them if you need to know. Maybe if it runs across the motor, they want it "Heat Wrapped". Any wire near exhaust or motor, should be protected by raising it up, reroute or loom. PVC goes to 125 F and GXL goes to 250 F.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | | | | Joined: Jul 2000 Posts: 2,191 Insomniac | | Insomniac Joined: Jul 2000 Posts: 2,191 | Drawings should have a table explaining what any abbreviations used actually mean. Or there should be specifications that accompany the drawing to provide the explanation.
My guess is that it refers to the wire insulation; HW means heavy wall? Hot, shaky engine is a nasty place for a small 18 ga wire. Extra insulation would be a good idea, it seems to me.
Gord 🇨🇦
----
1954 1/2 ton 235 4 speed
| | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 |
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Chuck M
From South Florida
Joined Fri Jul 14 2017 02:20 PM
Last Seen Tue Jan 01 2019 08:56 PM
Total Posts 8 (New Guy) [not so new; just not a frequent visitor] | | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 |
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | | | | Joined: Jul 2017 Posts: 13 New Guy | | New Guy Joined: Jul 2017 Posts: 13 | New guy did not go south - just had my head under the hood and in the dashboard for a while!
The schematic I am referring to is that which is in the GMC shop manual for my vehicle - it most definitely lists 'HW' - perhaps the shop manual is different than the "official 55-59 GMC manual schematic" someone referred to.
I'm not using an aftermarket harness but trying to do things the way the factory set it up with respect to color, gauge, etc. I've checked the manual and there is no index for abbreviations so I'm thinking this was a 'rogue' draftsman or engineer.
Any way, thank you for the input. | | | | | Joined: Apr 2005 Posts: 7,440 Bolter | | Bolter Joined: Apr 2005 Posts: 7,440 | Chuck, no problem with your short vacations. You must understand the folks most likely to answer your question check the “Bolt” every day and some more than once. It’s hard for them to understand the several days absence. The fact you are working on your truck is as good an excuse as anyone could have. I don’t think we have an answer for your HW question. Don’t give up on us, we usually have all the answers and then some whether you want them or not. 
Martin
'62 Chevy C-10 Stepside Shortbed (Restomod in progress)
'47 Chevy 3100 5 Window (long term project)
‘65 Chevy Biscayne (Emily)
‘39 Dodge Business Coupe (Clarence)
“I fought the law and the law won" now I are a retired one!
Support those brave men/women who stand the "Thin Blue Line"! Hug a cop!
USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
| | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 | I've seen draftsmen sneak in their initials on drawings. Looks like old Howard Witherstinker got his in there.
Or if you want to be more politically corrupt, we call them Drafters now.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | |
|
|
