1994 Ford Ranger

Auto 131 Lab Experience Report

Part 1: Vehicle Information

Student name(s):

Efrain Gonzalez and Justin Serr

Vehicle year, make, model:

1994 Ford Ranger

Customer’s name & repair order number:

Denis Taylor

Customer’s concern(s):

Headlamp switch is not working properly and needs to be replaced. You have to play with it a lot in order to get the

headlights to turn on and off. The headlights, taillights, and dash light will not all turn on at the same time.

Part 2: Documentation

Document the steps you took to diagnose and repair the vehicle—in the order that you did them. Write every step

—even if you made mistakes and now wish you would have done it differently. Begin when you picked up the keys,

end when you returned them. BE DETAILED & INCLUDE PHOTOGRAPHS!

1. We picked up the keys to the 1994 Ford Ranger from the office at Austin 106 at BYU-Idaho. We drove it to

the Agriculture Engineering building and parked it inside the lab.

2. We started by playing with the headlamp switch to verify the customer’s concern.

3. We confirmed that the headlights, taillights, and dash light were not all turning on at the same time. The

taillights would not turn on at the same time as the headlights, sometimes the dash light would turn on at

the same as the taillights, and the dash light would not turn on at the same time as the headlights.

4. We turned the headlights on and noticed that the right headlight bulb was not working and only the left

headlight bulb was lighting up.

5. We turned the switch to turn on the high beam lights on and noticed that the high beam lights were not

working.

6. As we were doing a visual inspection, we noticed that the battery had some corrosion on the terminals.

7. We went online onto ProDemand to look up a wiring diagram for the headlamps circuit and also to see if we

could find any TSB’s on this kind of problem.

8. We put our vehicle’s information into ProDemand and started to look up wiring diagrams to find one for the

headlamps.

9. We found a wiring diagram for the headlamps circuit and printed it.

10. We looked for TSB’s on problems with the headlamp switch on ProDemand and Google but were not able to

find any.

11. We studied the wiring diagram for the headlamps circuit and started to formulate a plan to diagnose the

circuit.

12. Our plan was to visually inspect the headlight bulb that was not lighting up, check the power and ground

cables for the bulb, and work our way up the diagram.

13. We pulled out our multimeter, set it to measure voltage drop, connected our leads to the battery terminals,

and checked for the battery’s state of charge. The multimeter read 12.36 volts. We deemed the state of

charge as close enough to 75 percent.

14. We then pulled the headlight bulb that was not lighting up out to check it for voltage drop and, as soon as

we pulled it out, it lit up.

15. We were confused by the bulb’s intermittent problem but proceeded to check it for voltage drop.

16. The wiring diagram for the headlamps circuit indicated that the wire for power was red with a black tracer

and the wire for ground was black.

17. We stuck a T-pin in the back of the of the bulb’s terminals, along the power and ground wires, to check for

voltage drop.

18. We set our multimeter to measure voltage drop and connected our leads to the T-pins back-probing the

bulb’s terminals. The multimeter read 11.56 volts. We determined that it was dropping most of the volts.

19. We took the lead off the T-pin along the ground wire and connected it to the battery’s negative terminal to

measure voltage drop on the ground side of the circuit. The multimeter read 4 millivolts, which equals out to

.004 volts.

20. We took the lead off the T-pin along the power wire and connected it to the T-pin along the ground wire,

and we took the lead on the battery’s negative terminal and put it on the positive terminal to measure

voltage drop on the power side of the circuit. The multimeter read 577 millivolts, which equals out to .577

volts.

21. We determined that there was resistance in both the power and ground wires but nothing out of the

ordinary but we decided to service the battery and make sure that the corrosion on it was not creating any

resistance.

22. We pulled the battery out, cleaned the terminals, cables, and the battery itself. When we pulled the battery

out, we noticed that there was a huge pile of battery acid underneath the battery. We cleaned it out and put

the battery back in. We sprayed the terminals with a chemical that prevents corrosion and hooked

everything back up.

23. We went back to the light bulb that kept turning off and on. As we were working around the bulb we noticed

that it was getting extremely hot. It would instantly melt our gloves as soon as we made contact with it.

24. We noticed that the bulb was melting its connector and that it was most likely because the blub was

creating too much resistance.

25. We determined that the bulb was not supposed to be getting that hot and that it needed to be replaced.

26. We went online onto Mitchell Manager and ordered a new set of high/low beam headlight bulbs from Napa

Auto Parts for a 1994 Ford Ranger 2.3 L.

27. We received the bulbs from Napa Auto Parts and recorded the invoice on Mitchell Manager. We put the

invoice with our name and repair order number in the invoice box.

28. We took both headlight bulbs out and replaced them with the new set of bulbs.

29. After taking them out, we noticed that the left headlight bulb was different than the right headlight bulb and

determined that that was the cause for the high beam lights not working.

30. We used the switch to turn the headlights on, and the high beam lights on, and we confirmed that replacing

the bulbs was the correct repair for that problem.

31. We called the customer, Dennis Taylor, to update him on how the repair on his vehicle was going. He

mentioned the problem with the taillights once more. He said that the switch would only allow you to either

have the taillights on or the headlights on but not both on at the same time.

32. We played with the switch once more and confirmed that the problem was still there.

33. We decided to do a battery system test and a hand held test to get that checked off our lab sheet.

34. The battery failed both tests so we inspected the battery more closely.

35. We noticed that the battery was leaking from the bottom.

36. We proceeded to make a plan to diagnose the headlamp switch.

37. We went online onto ProDemand to find a wiring diagram for the headlamp switch circuit.

38. We made a second plan using the headlamp switch wiring diagram.

39. Based off the problems, we decided to start at the switch itself and move our way towards wherever the

switch pointed us, power or ground.

40. We went back to ProDemand and printed off the removal steps for the headlamp switch.

41. We then proceeded by pulling the dash apart and removing the switch as instructed.

42. At this time class was over so we went to pull the truck out and it wouldn’t start even with the assistance of

the booster pack.

43. So we pushed the truck out and decided to look more into it during the next lab.

44. We decided we were going to finish fixing the taillights and then find out why it wouldn’t start.

45. Now that we had the headlamp switch out we tested it while in the on position, where all the lights should

have been working together. First, we tested the power for the taillights which were not working. No power

was coming in on the taillight side.

46. Next, we checked the power and ground for the headlight portion of the switch, we found that there was

power getting to the headlight portion.

47. We decided to use jumper wires to go from the power on the headlight side to the taillight side to see if they

would turn on. They did turn on when we used the jumper wires.

48. We determined that the problem was not in the switch and was on the power side so we decided to go the

fuse next.

49. We checked the fuse and it was blown.

50. We replaced the fuse and the taillights worked.

51. We then played with the wires and the switch to see if we could get the fuse to blow again and we could

not.

52. While working on the switch we noticed the turn signals would not work as well. Not all the bulbs were

lighting properly. But when we turned on the hazards, all the bulbs lit up perfectly.

53. We checked the fuses since we were already there and because we wondered if they were related.

54. The fuse for the turn signals was not getting power and was not blown.

55. But class was almost over so we decided to wait on the turn signals and see if we could get the truck to start.

56. We talked about our collection of smaller problems and how the truck would not start and decided we

would start by pulling the battery out again but this time we would replaced it with a booster pack to see if

all the components would work any better and see if the truck would start.

57. The truck started right up and the blinkers and dash lights worked perfectly.

58. We determined that the battery was not working properly and was most likely sacrificing certain electrical

components because it was not producing the correct amount of voltage.

59. We decided to replace the battery.

60. We called the customer, Dennis Taylor, to make sure he was okay with us purchasing a new battery. He

approved the purchase.

61. We called Napa Auto Parts and ordered a new battery for a 1994 Ford Ranger 2.3 L.

62. When we got the battery, we returned the core and turned in our invoice with our name and repair order

number into the invoice box.

63. We replaced the old battery with the new one and tested all the electrical components to make sure the

replacing the battery was the correct repair.

64. Everything worked the way it should. All the problems disappeared.

65. We put the headlamp switch back in and put the dash back together.

66. Then we took the truck for a short test drive to see if the fuse would blow again and it did not.

67. We then called the customer, Denis Taylor, to let him know where we were at and that his vehicle was

ready.

68. We confirmed that he could come get it and let him know where we were parking it.

69. Lastly, we parked the truck and gave the keys and the repair order sheet to the office in Austin 106 at BYU-

Idaho.

Part 3: Reflection & Analysis

What parts of this process went well?

We worked great as a team and were able to think things through and figure out how to make a plan to diagnose

the problem. We did a good job at taking the skills we learned in class, about circuits and electricity, and put them

into a real world application. Our ability to read, understand, and interpret the wiring diagrams was crucial to the

whole process of repairing the vehicle. We were able to successfully diagnose the problem, perform, and confirm

the repair because we followed the correct steps to diagnose, and repair the vehicle (the 7 steps).

Which steps were most critical in your diagnosis process?

The most crucial steps in our diagnosis process was our studying of the components and our planning to diagnose

the problems with them. We went back to those steps repeatedly, which granted us the most success. Every time

we went back to re-study and re-plan we learned and got better at it.

What kept you from being as effective as you could have been?

We had a few setbacks in repairing the vehicle. One of those being our planning. Because of lack of experience, we

did not really know where to start or where to end. We followed the 7 steps but not as effectively and correctly as

we could have. We were also very unexperienced using ProDemand and Mitchel manager, which significantly

slowed us down. The lack of experience was probably our biggest problem repairing this vehicle.

Now that you can look back on how this project unfolded, what would you like to do differently next time?

We would have been more thorough in the 7 steps, especially in our visual inspection of the vehicle and in our

planning. If we were to have been thorough in our visual inspection, we would have noticed that the battery did not

look so good, would have proceeded to testing it, and would have found out that it was bad. If we were to have

done this, we would not have dealt with rolling it up hill and thinking we did something wrong when the vehicle did

not start that one lab day. Our planning was more of an idea of what we were going to do rather than a step by step

process. If we would have been more thorough in our planning, then we would have not had to re-plan so much. We

spent a lot of time walking from our vehicle to the computers and back to our vehicle again. If our planning would

have been better, the project would have taken us as long as it did.