Where is the starter relay on a 2007 Dodge Ram 2500?

The starter relay is located inside the under-hood power distribution center (PDC), also known as the IPDM, on the driver’s side of the engine bay. It’s a small relay labeled “S” or “START” inside that relay box.

In the 2007 Ram 2500, whether equipped with a 5.7-liter Hemi or a 6.7-liter Cummins, the starting circuit is controlled by this relay inside the PDC/IPDM. Access is gained by removing the PDC cover; the box contains several relays and fuses, and a diagram on the cover shows the exact position of the Starter relay. If you’re troubleshooting, you’ll be checking power to the relay coil and the contacts that feed the starter solenoid.

Locating the Starter Relay inside the PDC/IPDM

The steps below guide you to identify and locate the correct relay inside the under-hood PDC/IPDM.

• Open the hood and locate the large, multi-relay fuse box mounted in the engine bay on the driver’s side or near the battery. The exact position may vary by truck, but it’s the prominent black/gray box with a removable cover.


• Remove the PDC cover. The underside or the inside of the cover has a diagram labeling each relay, including the Starter (S) or START relay.


• Look for the relay labeled S, START, or ST; this is the starter relay that controls the heavy-current circuit to the starter solenoid.


• Note the terminals on the relay: typically two large power posts and two small coil/control posts. The coil posts connect to ignition/trigger signals; the heavy posts connect the battery feed to the starter solenoid.


• If you cannot identify it by the diagram, refer to the service manual for the exact pinout for your engine variant (5.7 Hemi vs 6.7 Cummins), as the layout can differ slightly.

Concluding: Identifying the Starter relay in the IPDM/PDC centralizes troubleshooting; swapping a suspect relay with a known-good one or testing the coil and feed circuits can confirm its operation without replacing expensive components.

Testing and verifying the starter relay

Before replacing hardware, you can test the relay and related circuits to confirm where the fault lies.

• With the ignition off, remove the PDC cover and locate the Starter relay as described above.


• Perform a visual inspection for signs of damage or corrosion on the relay contacts and the surrounding wiring.


• Swap the Starter relay with another identical relay in the PDC (temporarily) to see if the starting issue follows the relay. If the car starts with the other relay, the original is faulty.


• Measure the coil resistance across the small terminals with a multimeter; typical values are in the range specified by Mopar service data (often tens to hundreds of ohms). If it's open or dramatically out of range, replace the relay.


• Check for 12V present at the relay coil input when the ignition is in the run/start position and 0V when off. Also check that the output side to the starter solenoid receives voltage when cranking.


• Verify the wiring to the starter and the battery; if the relay and coil test good, the issue may be the ignition switch, wiring harness, or the starter itself.

Concluding: A careful relay test can prevent unnecessary replacement. If in doubt, consult a service manual or a professional technician, as wiring harness routes and IPDM layouts can vary between 5.7 Hemi and 6.7 Cummins configurations.

Notes on engine variant and layout

The exact physical location may vary slightly by engine type and production run, but the general principle remains: the Starter relay sits inside the under-hood Power Distribution Center/IPDM rather than as a standalone unit on the fender. The cover diagram is your best guide.

Summary

The starter relay on a 2007 Dodge Ram 2500 is not a conspicuous standalone relay on the engine bay; it lives inside the under-hood IPDM/PDC. Access the box, remove the cover, and locate the relay labeled S or START. If problems arise, test or swap the relay with a known-good unit and check related wiring and the starter solenoid. This approach applies to both the gas 5.7 Hemi and the 6.7 Cummins variants, with layout differences possible between models.

Where is the relay on a 2007 Dodge Ram?

The fuel pump relay for your 2007 Dodge Ram 1500 is located inside the vehicle's cabin, specifically within the Totally Integrated Power Module (TIPM) positioned under the driver's side dashboard.

How to tell if the starter relay is bad?

A bad starter relay can cause the engine to not start at all, intermittent starting issues, or a clicking sound when you turn the key. Other symptoms include the starter motor remaining engaged after the engine starts, a grinding noise, or even a burning smell. 
This video explains the symptoms of a bad starter relay: 59sCar FixYouTube · May 2, 2024
Common symptoms of a bad starter relay

• No-start condition: The most common symptom is that nothing happens when you turn the key, with no cranking or clicking sounds, because the relay can't complete the circuit to the starter motor. 
• Intermittent starting: The car may start fine sometimes but refuse to start at other times. This is often due to pitted contacts inside the relay that make a poor connection. 
• Clicking sound: A single click when you turn the key can indicate a bad relay that is struggling to send full power. 
• Starter remains engaged: In rare cases, the relay can get stuck in the "on" position, causing the starter to continuously run after the engine has started. This can be accompanied by grinding noises and may damage the starter motor and flywheel. 
• Slow cranking: If the relay isn't providing enough power, the engine may crank slowly before it starts. 
• Electrical issues: Dimming headlights or other electrical problems while trying to start can also be a sign of a failing relay. 

This video demonstrates how to test a starter relay with a multimeter: 36sWard WrenchingYouTube · Apr 17, 2023
How to confirm the relay is bad

• Check other electrical components: If your other electronics (like the radio and lights) are working correctly, a bad starter relay is a more likely culprit than a dead battery. 
• Listen carefully: With a helper, listen for the clicking sound. The absence of a click when turning the key to the start position points to a relay or ignition switch issue. 
• Test with a multimeter: A mechanic can use a multimeter to check for voltage at the relay's control terminals when the key is turned to the "start" position. If voltage is present but the relay doesn't send power to the starter motor, the relay is likely faulty. 

Why is my Dodge Ram 2500 not cranking?

A Ram 2500 might not start due to issues with the battery, starter relay, or ignition switch. Other common culprits include a weak/dead key fob battery, loose or corroded battery terminals, a malfunctioning neutral safety switch, or problems with the starter motor itself. 
Common issues to check 
This video explains 5 common reasons why a car won't start, even if it has power: 52sFixITYouTube · Jan 23, 2025

• Battery problems: A weak or dead battery is a frequent cause. Check the voltage; anything below 12.0612.0612.06V is low. Also, inspect the terminals for corrosion or loose connections, as this can block power even if the battery is good. 
• Starter relay and fuses: A faulty starter relay can prevent power from reaching the starter motor. Check the fuses in the under-hood fuse box, as a blown fuse can also cause a no-start situation. 
• Ignition switch: A problem with the ignition switch can disrupt the electrical flow needed to start the vehicle. 
• Key fob battery: For push-button start models, a weak key fob battery can prevent the system from recognizing the fob and allow starting. 
• Neutral safety switch: This switch prevents the truck from starting unless it's in Park or Neutral. If it malfunctions, it can block the starter from engaging, even if the truck is in the correct gear. 
• Starter motor: The starter itself can fail. If you hear a clicking sound, it often indicates the starter isn't getting enough power, but a bad starter motor can also fail to crank the engine. 
• Wiring and grounds: Poorly connected or damaged wiring, especially ground straps, can cause a variety of electrical issues, including a no-start condition. 
• Fuel system: While less common for a "no crank" situation, a lack of fuel pressure can prevent the engine from starting once it cranks. 
• Electronic issues: Some electronic problems, such as communication failures between control modules, can prevent the truck from starting. This can sometimes be accompanied by the system rebooting when you try to start it. 

Troubleshooting steps

1. Check the battery: Test the battery voltage. Clean and tighten the terminals. 
2. Inspect the key fob: If you have a push-button start, try a new key fob battery or the emergency start procedure. 
3. Check fuses and relays: Locate the fuse box and inspect the starter relay and related fuses. It's best to test them with a multimeter, as a fuse can look good but still be bad, notes this YouTube video. 
4. Listen to the starter: If you hear a single click, it often points to the starter relay or a weak starter. If you hear no sound at all, it could be the ignition switch, neutral safety switch, or a power delivery problem. 
5. Test the starter: A professional can test the starter for voltage, or you can check it yourself with a multimeter to see if the signal is reaching the starter motor when the key is turned. 
6. Examine wiring: Look for any loose or corroded wiring, especially around the starter, battery, and ground points. 
7. Verify fuel: If the engine cranks but doesn't start, confirm you have enough fuel and check the fuel pressure if possible. 

Where is the starter motor relay located?

Starting relay position
It might be in the power box (also called the fuse box), under the dash panel, or near the right fender. In most cars, you'll find it under the hood in a big box with a black cover. This is where all the car fuses and relays are kept.