Keeney Auto & Diesel

Call Directions Website Contact the business

Keeney Auto & Diesel Diagnostic Excellence

Intermittent MAP sensor failure.This vehicle was intermittently dropping into limp mode with P0106 and P0107 MAP sensor ...
10/20/2026

Intermittent MAP sensor failure.

This vehicle was intermittently dropping into limp mode with P0106 and P0107 MAP sensor codes and a wring repair was already attempted before it came here.

While monitoring live data and manipulating the engine harness, the MAP signal briefly failed. Circuit testing showed the 5V reference, low reference, and signal wiring operating correctly, but the fault disappeared once the connector was moved from its normal position.

Intermittent failures are the most difficult issues to track down. This is why we have such a light-touch and strict, methodical, approach to vehicles with intermittent problems.

Intermittent stalls can be hard to catch.This vehicle would intermittently stall while driving, then usually restart wit...
10/15/2026

Intermittent stalls can be hard to catch.

This vehicle would intermittently stall while driving, then usually restart without issue. A stored crank sensor code gave us a direction, but the failure still needed to be verified.

The crank sensor was monitored directly with a scope during multiple test drives. Eventually, a single failure was captured that lined up exactly with an engine hesitation lasting only about 0.05 seconds.

The crankshaft position sensor was failing intermittently and was replaced.

Sometimes the entire fault lasts less than the blink of an eye. This is why we are so keen on our selective use of electronic tools and oscilloscopes.

On this 2005 Duramax, we had a crank, no start.Testing found the engine wasn't building fuel rail pressure. Further test...
10/13/2026

On this 2005 Duramax, we had a crank, no start.

Testing found the engine wasn't building fuel rail pressure. Further testing showed no fuel vacuum being generated on the suction side of the high pressure pump.

After manually priming the system, a fuel leak became apparent at the fuel filter assembly.

The filter assembly was replaced, restoring proper fuel supply and engine operation.

No rail pressure. No fuel vacuum. Find out why.

Multiple electrical problems on this one.This truck had everything from lights coming on after shutdown to intermittent ...
10/07/2026

Multiple electrical problems on this one.

This truck had everything from lights coming on after shutdown to intermittent no-starts, radio and power steering loss, and eventually a dead battery.

Testing found seven modules contributing to the drain. Network testing isolated the primary fault to the instrument cluster. The cluster was waking the CAN network, which then woke the BCM and several other modules.

The instrument cluster had failed and requires replacement.

Multiple symptoms. Follow the network. Find what wakes up first.

New Case Study Is Up → [https://youtu.be/Lcb1GJURIuA]Engine dies when the headlights or A/C are turned on. The washer pu...
10/06/2026

New Case Study Is Up → [https://youtu.be/Lcb1GJURIuA]

Engine dies when the headlights or A/C are turned on. The washer pump also runs with the headlights and turn signals behave erratically.

2010 Lincoln Town Car
Key points:
• Headlights caused the PCM to completely lose communication.
• Circuit testing showed the lighting and washer circuits were finding an unintended ground path through each other.
• Testing isolated the problem to a failed Ground 102 connection. Providing a known-good ground immediately restored proper operation.
• The ground connection was disassembled, cleaned, and restored.

Results: Headlights, turn signals, hazards, washer system, PCM communication, and engine operation all returned to normal.

Hatch window stopped working. The motor was running, but the window wasn't moving.Testing confirmed the wiring was intac...
10/01/2026

Hatch window stopped working. The motor was running, but the window wasn't moving.

Testing confirmed the wiring was intact and the regulator assembly along with the glass moved correctly.

The window motor was removed and powered directly. The motor operated internally, but stripped gears prevented it from driving the regulator.

Failed motor, not a wiring or regulator problem. Test the system. Replace what actually failed.

Two alternators later, still not charging.The charging failure started immediately after the vehicle was used to jump-st...
09/29/2026

Two alternators later, still not charging.

The charging failure started immediately after the vehicle was used to jump-start another vehicle. Two alternators had already been replaced, but the problem remained.

Further testing confirmed the alternator itself was capable of charging and the control wiring, computer powers, grounds, and communication circuits tested correctly. The PCM was trying to command the alternator to charge, but couldn't complete the task.

The fault was isolated to a failed PCM alternator driver.

Two alternators replaced. Neither was the problem. Test the circuit before replacing the part.

Intermittent engine shutdown traced to the coolant level circuit.The truck would intermittently stall after warming up, ...
09/28/2026

Intermittent engine shutdown traced to the coolant level circuit.

The truck would intermittently stall after warming up, especially while pulling a loaded trailer. Each shutdown was preceded by an engine protection warning.

Testing during the failure showed the coolant-related fault counter incrementing with each shutdown. The coolant level system was isolated and bypassed with a resistor, and the truck then ran without issue.

Duplicate the failure. Watch the data. Isolate the circuit.

New Case Study Is Up → [https://youtu.be/J8g1UUjz5a0]Vehicle: 2014 Dodge Challenger 5.7LClient concern: Transmission stu...
09/25/2026

New Case Study Is Up → [https://youtu.be/J8g1UUjz5a0]

Vehicle: 2014 Dodge Challenger 5.7L
Client concern: Transmission stuck in limp mode with only first gear and reverse.

Key points:
• TCM was offline with multiple communication faults.
• CAN communication and ground tested correctly.
• TCM power intermittently dropped from battery voltage to less than 0.5V.
• Testing isolated the intermittent power loss to the transmission relay.
• A higher-quality relay was installed and the vehicle was repeatedly heat soaked, cold soaked, started, and driven to verify the repair.

Result: Seven months later, the problem has not returned.

Even the headlights can shut an engine off.This engine would die and activate the windshield washer pump whenever the he...
09/23/2026

Even the headlights can shut an engine off.

This engine would die and activate the windshield washer pump whenever the headlights or A/C were turned on.

Testing showed that applying power to any circuit in the right front headlamp assembly caused PCM communication to drop out and the washer pump to activate.

A bypass ground at the headlamp eliminated every symptom.

The circuit was traced to a poor ground connection at G102/G103. Correcting the connection restored normal operation.

One bad ground. Multiple unrelated symptoms. Test the circuit, find what they have in common.

Address

8307 Dayton Pike
Soddy-Daisy, TN
37379

Opening Hours

Monday 11am - 8pm
Tuesday 11am - 8pm
Wednesday 11am - 8pm
Thursday 11am - 8pm
Friday 11am - 5pm
Saturday 12pm - 5pm

Telephone

+14234010588

Website

Alerts

Be the first to know and let us send you an email when Keeney Auto & Diesel posts news and promotions. Your email address will not be used for any other purpose, and you can unsubscribe at any time.

Contact The Business

Send a message to Keeney Auto & Diesel:

Shortcuts

Share

Category