1994 Ford Crown Victoria, No Tail lights

Vehicle arrived with no tail or park lights. Customer stated that they work sometimes. As this is a very common problem with almost all Ford vehicles that have a pull knob type headlight switch I went straight to the problem and documented to help others.

First I gained access to the headlight switch. I could see the damage to the wiring from the outside of the assembly. Brown wire was burnt at the top left corner of the first picture.

Unplugged connector from switch and more damage was evident. The switch and the harness had to be replaced.

A quality replacement harness is currently available online from The Electric Connection. I installed the replacement harness connector by first transferring the undamaged terminals and wires from the original to the replacement connector.

After all good wiring had been transfered I only had to replace the one burnt wire and terminal. Sometimes more have to be changed.

I then reassembled to a new Motorcraft headlight switch, tested and reassembled the dash.

P0442, 1997 Mitsubishi Eclipse

Car was dropped off with the check engine light on. Checked codes and found P0442 stored for a small evap leak. Looked vehicle over and found nothing. Did some research and found that the common failure is in the rollover valve located in the top of the fuel tank. What happens over time is that the tube on the rollover valve has slight pressure applied to it by a body panel and it develops a crack which is where the small evap leak comes from. The repair is fairly simple in that if you can lower the tank about 3″ to 4″ while maintaining support on the tank then you can access the rollover valve screws from the driver’s side with one arm and over the rear of the tank with the other arm. There are three attaching screws and the single hose that hold the rollover valve in place. Some people have suggested beating the floor panel up and away from the valve but I figured it will probably last another ten or eleven years and the tank would have to be well out of the way to be able to modify the panel.

2000 Cadillac Deville Erratic Compressor Operation

Cadillac Deville was sent to shop from another facility with complaint of a/c cycles off and will not come back on for several minutes and vent temperature goes warm.

Checked codes and none were stored in the ECM, DIM or IPM. All data looked good and then the compressor cycled off after running at 2000 rpm for about 10 minutes. Data still looked good including clutch relay request and actual condition.

Tested clutch relay signals at relay base with voltmeter, all tested good. Clutch cycled back on while testing so I had to run again for extended time for complaint to return. Double checked and all signals were present at relay.

Raised vehicle and performed visual inspection. Spotted a sensor at rear of compressor. Consulted Mitchell On Demand and found nothing listed. Went up to 2004 looking for reference to sensor and finally found it. Sensor turns off compressor at 311 degrees and is outside of computer control or diagnostic ability.

Checked to see if system was overcharged. It was actually undercharged by 8 ounces.

While system was recovered I inspected the orifice tube only to find debris on the screen. Replaced tube and recharged system to confirm what I already knew. The compressor was coming apart and the condenser was restricted. I confirmed this by doing a temperature drop test at the condenser input and output lines. 80 degree drop at 2000 rpm after 1 to 3 minutes. Way too much.

System needed the compressor, condenser, accumulator, orifice tube and compressor hoses replaced. Discharge hose had been leaking and suction hose had been updated. Flushed the evaporator and remaining lines. Added oil, vacuumed and recharged system. Works perfect!!!!!!!

2004 Chevrolet Silverado 2500HD , 6.0 Vin U Misfire

Vehicle came in the shop, with the SES light on and an obvious misfire. Previous shops had replaced plugs and wires, removed cats, replaced both bank 2 oxygen sensors, the ECM and had swapped positions of coils and injectors for cylinder #6. I scanned vehicle and found a misfire present on #6 cylinder on a regular basis. Performed fuel trim reset and vehicle ran better but misfire soon returned. Short term fuel trim was at -17 and long term was -30. Injector pulse with was 1.2 ms shorter on bank 2 than on bank 1, bank 2 sensor 2 was staying at about .038 volts and bank 2 sensor 1 would stay fairly high and occasionally spike to 1.0+ volts.
I disconnected b2s2 connection thinking it was shorted and would improve the misfire by setting a default value in the ECM. It helped but b2s1 was still spiking high. Plugged b2s2 back up and disconnected b2s1. Default voltage of .45 set for b2s1 and b2s2 started working properly and misfire was much improved. Suspected that b2s1 sensor was faulty even though it was new. I was looking closely at the plugs between b1s1 and b2s1 to see if I could remove both and swap sides to see if problem would follow the suspected faulty oxygen sensor when I spotted the problem. The tan wire was broken at the chassis harness connector for the b2s1 oxygen sensor. Mitchell On Demand listed it as HO2S low signal, I believe it is actually a return ground signal. Repaired wire, cleared codes and test drove. Problem fixed!!!!!!!!!!!!!!!!

2000 Cadillac Deville, Fuel Gauge Reads Full All Of The Time

Customer stated that fuel gauge always reads full but the trip computer is keeping track of fuel mileage and he has been using it to monitor fuel level.

Checked codes and found codes stored for both fuel level signal voltage high and low. Consulted repair information and found little help. Wiring diagram shows signals from tank go into PZM (also known as BCM), PZM sends information to instrument cluster. Could not find any info on testing so I decided to go with experience and started at the tank sending unit.

Well I was working alone and could not see the gauge while testing so I decided to test at the PZM. It is located behind the back seat and I could watch the gauge through the back glass. I disconnected the PZM and tested the tank sending unit resistance at the brown and violet wires. Open. Well, I know the tank sending unit is faulty but is the rest of the system okay?

I installed my trusty decade resistance box and the gauge reacted properly. Here are the resistance specs I was able to establish.

215 Ohms Full
167 Ohms 15 Gallons
121 Ohms 10 Gallons
78 Ohms 5 Gallons
54 Ohms 3 Gallons

1999 Pontiac Montana Fuel Pump Fuse Blows

Customer stated that he has installed two fuel pump assemblies within a few days and fuel pump fuse continues to blow.

Removed the fuel pump fuse and relay and replaced with fused jumper wires that have manual reset circuit breakers install. This allowed testing without having to constantly having to cycle the key for fuel pump operation.

Circuit breaker would trip instantly. Time to start isolating. First raise vehicle and disconnect fuel pump harness at floor pass thru connector located behind driver’s seat.

Short still present. Located and disconnected harness junction block at right front kick panel.

Short was now gone. Short has to be under carpet in passenger compartment. No signs of body damage and it did not appear that the seats had been out. So where to start? I decided to look at the connector that passes thru the floor behind the driver’s seat. Lifted the carpet and saw a metal shield over the connector and some gummed up wiring.

Knew that I was close so I drilled out the rivets that were holding the plate down. Lifted the plate and there was the short.

Removed pass thru connector, removed and replaced burnt terminals and wiring. Cleaned remaining terminals and installed dielectric grease as there was also signs of water intrusion. Reassembled connector to floor board with bolts and nuts and reassembled vehicle. Actual repair time took about five hours from start to finish. It can be done in less than two with this info.

1999 Buick LeSabre, A/C Controls Blinks, Ticking Under Dash

This car came in with the complaint of the a/c control head was blinking and there was a ticking sound under the dash. Also the customer stated that the headlights go out when this happens. Luckily the symptoms were present along with others. The oil gauge would jump with the ticking sound and I noted that the right turn indicator would glow with the headlights turned on.

Being confronted with so many symptoms it is always best to pick one and target it only until completed or until you reach a road block and cannot continue. The right headlight was the easiest so I chose to investigate it first. Checked powers and grounds and found ground signal missing.

Consulted wiring diagram and found ground located at right front inner fender panel. While there I also checked for ground locations for the a/c system. Guess what, right front inner fender panel.

Located, cleaned and tightened all grounds at ground stud on right front inner fender panel and rechecked vehicle symptoms. All were cleared up!!!!

2001 Ford Ranger, Fuse #2 Blows

2001 Ford Ranger with automatic transmission came in with fuse #2 in the interior fuse block blowing for the customer daily. Customers main complaint was that the a/c would stop blowing when the fuse would blow.

Inserted fused jumper wire that uses ATO/ATC fuses. Cheaper fuses to blow and can access wiring to do amp draw testing.

Ran vehicle and operated a/c while wiggling wires. No problem found. Moved vehicle and fuse blew as shifter was moved through reverse. Checked reverse light wiring (okay). Fuse would no longer blow. Drove vehicle, no problem. Consulted wiring diagram and found that fuse #2 supplies power to the overdrive switch and I knew what the problem was. Removed lower panels and steering column shroud and found the shorted wiring harness for the overdrive switch at the shift lever pivot point.

Locate and disconnect O/D switch harness connector and confirm that the short is gone.

The actual short is shown in the last picture. It is the copper colored spot just above and slightly left of the shifter pivot pin. Wrapped with live rubber tape and electrical tape and reassembled. Fixed!!!!

2000 Cadillac Deville, 4.6L, Surging Idle and Stalls

2000 Cadillac Deville with 4.6L engine was sent to my shop for surging idle. The engine has been changed. The IAC valve, TPS and MAP have been replaced with oem parts. The IAC valve harness connector did have the terminals spread and there was poor contact between harness connector and IAC valve. Replaced the connector and surging was improved but still there. Checked data with Tech 2 Scanner and found IAC counts at or near zero, MAP was fluctuating with idle variations. Checked data further and the only thing that seemed out of place was the spark timing was shifting from -10 to +25 during surging idle condition. The higher the swing in the spark numbers the worse the surging was. Using the special function feature I found that the surging would almost go away with +10 degrees of timing added. The next step was to scope the cam and crank sensor patterns. Cam and crank patterns were good. What now? Research found that the computer can base its timing programs on either angle or time data and this works with the engine having an A and a B crank sensor. Maybe the sensors were plugged in backwards? Nope, different plugs. Well I was there anyways lets see if computer will recognise a missing sensor. Disconnected sensor A and cranked engine, SES light on, idle problem is gone but can tell base timing is off due to flat engine sound. Great, finally found someting that would make a difference. Went to ACDelco.com and looked up part numbers. Parts are listed as upper and lower and pictures are available. The upper had been disconnected and it was black in color. How come the picture of the part is grey? No it could not be! Removed both sensors and exchanged positions. Upper = Gray, Lower = Black . Cleared codes and cranked engine, PERFECT!!!
Although the plugs cannot be connected to the wrong sensor the sensors can be placed in the wrong hole. After fixing this vehicle and reviewing data I realized that the dead give aways for this condition are erratic spark timing and IAC counts that are not between 40 and 80 at warm idle. Hope this helps some one else.

2001 Chevrolet Cavalier Headlights Inop

2001 Chevrolet Cavalier came in the shop with no headlights. The service vehicle light is on and the DRL relay clicks several times when placed in gear with engine running. Checked power and ground at headlight bulb (required assembly removal). No switching grounds from dimmer switch. Located badly damaged harness connector under the battery tray. Cut out connector, extended wiring and reconnected. Headlights now work properly!