1. In-Vehicle and Under-Vehicle Inspection
CH 8.3
In-Vehicle and Under-Vehicle Inspection

2. Introduction
Regular inspection of a vehicle helps ensure the safe and reliable operation of a vehicle.
Types of inspections
Underhood inspection
Exterior inspection
Certain in-vehicle inspections
Under-vehicle inspection
Check fluid levels, lighting systems, etc.
Faults or concerns should be noted for service or repair.

3. Checking the Brake Pedal
Changes to how far pedal travels or to its resistance can be an indicator of problems.
Always check this before driving a vehicle in or out of the shop.
Listen for unusual noises. 3

4. Checking the Parking Brake
The parking brake is used to hold the vehicle in position when parked.
Automatic transmission owners may not know brake might not work at all until it is needed.
The parking brake cable can freeze in the applied position in climates with below-freezing temperatures. 4

5. Checking the Instrument Panel Warning Lamps
Warning lamps can indicate faults or proper operation with various systems.
The warning lamps perform a self-check each time the ignition is switched on or the engine cranked.
Observe the action of the lights when operating the vehicle to determine if additional services may be required. 5

6. Checking the Horn
Usually operated by a relay or by vehicle body control module (BCM)
There may be a single horn or a pair of horns.
With two horns, one will sound at a lower pitch than the other.
Horns are located at front of vehicle behind the grill or bumper.
Easily checked before entering the shop 6

7. Under-Vehicle Inspections (1 of 9)
Systematic visual inspections of all major vehicle systems
Note any faults to discuss with supervisor.
A good way to get a feel for the overall condition of the vehicle 7

8. Under-Vehicle Inspections (2 of 9)
The steering area
Check for any excess movement in driveshaft universal joints.
Look for any dents or bending of the shaft.
The front-wheel drive axles
Includes the constant velocity joints and dust boots
Look for cracked, torn, or leaking boots. 8

9. Under-Vehicle Inspections (3 of 9)
The engine area
Check for coolant, oil, and fuel leaks.
Look for torn or cracked motor mounts, coolant hoses, and belts. 9

10. Under-Vehicle Inspections (4 of 9)
The transmission area
Includes the transmission case, clutch housing, external linkages, and wiring connectors
Check for fluid leaks, loose mounting bolts, and faults or looseness in the clutch mechanism or shift linkage. 10

11. Under-Vehicle Inspections (5 of 9)
The exhaust system
Clamps and bolts may need tightening on the exhaust system or on the exhaust system-to-manifold bolts or gaskets.
Check for signs of exhaust leaks, corrosion, or deterioration, including the exhaust hanger hardware.
Check the condition of any heat shields. 11

12. Under-Vehicle Inspections (6 of 9)
The parking brake cables
The cables are encased in a housing that attaches the parking brake lever or pedal to the rear brakes.
Check for rusted, frozen, broken, or crushed cables. 12

13. Under-Vehicle Inspections (7 of 9)
The driveshaft
Transmits power from the transmission to the rear axle on rear-wheel drive vehicles
Check for any excess movement in driveshaft universal joints.
Look for any dents or bending of the shaft. 13

14. Under-Vehicle Inspections (8 of 9)
The differential, rear axle, and rear suspension area
The rear axle includes the differential and axle shafts.
Look for leaks around the differential and check the rear shock absorbers, leaf springs, brake hoses, and lines. 14

15. Under-Vehicle Inspections (9 of 9)
The fuel tank
Metal or plastic
The fuel tank must be secure and fuel lines inspected for damage or abrasions. 15

16. Checking for Fluid Leaks (1 of 6)
The service bay should be clean and dry.
Distinctive colors, feels, and smells
Brake fluid
Clear or light amber looking for DOT 3 and DOT 4
DOT 5 is usually purple.
Slightly slippery
Has an unpleasant, slightly acid-type smell 16

17. Checking for Fluid Leaks (2 of 6)
Distinctive colors, feels, and smells (cont’d)
Automatic transmission fluid and some manual transmission fluid
Normally reddish in color
Very slippery and oily
Has an oily smell
Power steering fluid
Similar characteristics to automatic transmission fluid 17

18. Checking for Fluid Leaks (3 of 6)
Distinctive colors, feels, and smells (cont’d)
Coolant
Normally green, orange, or yellow in color
Some use a coolant that is red or light red.
Slippery
Has a sweet smell like syrup
Engine oil
Brown or black in color
Very slippery and a bit thick
Has an oily smell 18

19. Checking for Fluid Leaks (4 of 6)
Distinctive colors, feels, and smells (cont’d)
Manual transmission fluid
Light brown in color
Very slippery and thick like syrup
Has an oily smell
Gasoline
Clear in color
Evaporates easily
Has a distinctive gas odor 19

20. Checking for Fluid Leaks (5 of 6)
Distinctive colors, feels, and smells (cont’d)
Diesel
Dirty clear in color
Thin
Has an oily smell
Leaks will normally be more visible on a warmed-up vehicle.
Ask customer if there are any unusual smells when the vehicle is first started. 20

21. Checking for Fluid Leaks (6 of 6)
To check for leaks:
Drive the vehicle into a clean, well-lit work stall.
Ideally will have a lift
Use a flashlight to inspect underside of vehicle for any drips or wet areas.
While engine runs, wait to see if anything drips.
Identify fluid that is leaking and where it is from.
Always look toward top of wet area.
A leak under pressure can be sprayed a good distance from a small hole. 21

22. Summary (4 of 5)
Certain in-vehicle inspections and checks should be made as the vehicle is driven into the service bay.
The technician should always check the brake pedal feel and travel before driving into or out of the shop.
The parking brake should be checked as part of a routine safety or vehicle inspection.

23. Summary (5 of 5)
The many instrument panel warning lamps can indicate faults with various systems on the vehicle.
The horn can easily be checked before driving the vehicle into the shop.
With the vehicle safely lifted on a hoist, an underbody inspection is a good way to get a feel for the overall condition of the vehicle.

24. Credits
Unless otherwise indicated, all photographs and illustrations are under copyright of Jones & Bartlett Learning.