1994 GMC C1500 5.7L AT - No Crank

Friday

Hero Member
Joined
Apr 7, 2007
Messages
269
Points
18
Age
120
Location
Tecumseh, KS
Make
GMC
Model
C1500
Year
1994
Miles
189K
Engine
5.7L
1994 pickup. Not driving much in the pandemic. Drove it last 2 weeks ago. Yesterday went out to drive it and found no crank situation. All lights and gauges work. Found a rat nest in the engine compartment. Built in the last 2 weeks. Cannot readily see any chewed wires. I'm enclosing a schematic I found on-line for the truck, with the starting system outlined in red. I want to know if looks complete for my truck before I start tracking down the problem. I'm assuming the starter is not getting power, but everything else seems to be fine, aside from the 30 pounds of gravel the rat stacked on top of the intake manifold.
 

Attachments

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
6,879
Points
48
Yes, that looks typical for a GM of that era.
 

brcidd

Hero Member
Joined
Nov 16, 2006
Messages
275
Points
18
I always start at battery terminal connections.....especially if all lights work.
 

NickD

wrench
Joined
Aug 28, 2007
Messages
5,149
Points
48
Had a 1994 GMC starter, crawling underneath solenoid is mounted on the starter, has a large terminal, always hot with 12 V, smaller is for the solenoid coil, short jumper lead to the larger terminal should cause it to run that tells the starter is good. But knew ours was bad, GM used to make the starter housing out of a thick pipe, this one was a thin piece of sheet metal with a big hole rusted through it, and was dead. Definitely a throwaway item.

Had to get a new one. but if it does turn over not getting 12V from the ignition switch or from the neutral safety switch, or in some cases, would be all three. Banging my head with a hammer, can't remember if our had anti-thief that is another reason the key won't crank the engine.

Do remember, only way to set these up pulling the starter gear our engaged into the flywheel, from the extended tooth of the starter gear to the inside of the ring gear should be 0.020 clearance, to tight, starter gear will stick, to loose, may break a tooth off the ring gear, that is not easy to replace particularly in a 4WD.

To do this the flywheel cover has to be removed, another dumb idea from GM, on this thing torx screws were used and all the teeth on the inside were rusted out, much cheap junk from GM. Have to buy or make shims for the correct clearance

You don't mention if you have 4WD, this thing did, front drive shaft had to be removed along with other stuff, starter was buried under it. Don't know until you look.

On another GM product, ground the battery to the frame, that was stupid, rust to the block, had to make a new cable to ground it to the engine block, also need a heavy cable from engine block to a solid piece of frame is you can find it. Another vehicle that wouldn't crank when you hit the start with the ignition key.
 

grcauto

Hero Member
Joined
May 29, 2014
Messages
724
Points
28
Here's the factory diagrams for your truck from Mitchell. This is for the AT trans. If you have the MT I have those also. Let me know if you need anything.

Starter circuits here.

gmc.JPG

Engine/trans management here.

gmc1.JPG

gmc2.JPG

gmc3.JPG
 

Attachments

Last edited:
Top