No Start On Cold, Intermittently | Fuel Pump Relay Repair (Bypass)

🚗 2012 Chrysler Grand Caravan

Symptoms

• Car sometimes has a hard time starting, especially on cold; sometimes starts and dies.
• Starts fine with starter fluid.
• Fuel pump operates intermittently.

Diagnostics

• While cranking, ask someone to measure voltage on the M25 fuse in the under-hood fuse box (aka TIPM).
  • 
• If it doesn’t have a constant 12V while cranking, it means that the fuel pump relay (not serviceable, inside the fuse box) has failed and this article might help you repair the issue.
  • 📝 Note that if you just turn the ignition ON, fuel pump should be activated only for the first 2 seconds. It is normal.  In contrast, while engine cranking/running, it should be activated all the time.

Repair

There are at least 3 ways to fix the issue (i will describe the 3rd option in detail)

1. Change the TIPM (under-hood fusebox) and program it to the car.

It’s the most expensive solution; requires OEM tools to reprogram a new TIPM.

2. Replace fuel pump relay.

• Make pictures of the TIPM fuses location
• Open TIPM open
• Find the fuel pump relay on the circuit board
  0

  If someone has done this, post photos pleasex
• Order another one online with the same part number (or substitution)
• Replace it

It’s an inexpensive solution, but requires good soldering skills.  Keep in mind that though unsoldering a relay from a circuit board is generally not that hard (unless it has 10+ pins), it is still much harder than soldering it in, especially for a newbie.

Another option is to send it over to the specialists like

• http://www.verticalvisions.com/tipm-repairs.html

3. Wire in a Bypass Relay

This method is quite inexpensive and the easiest, in my opinion.

What you will need

• 20A fuse
• Inline fuse holder
  • 
• 30A 12V DC Relay
  • 
• 16-22 AWG wires
• Corrugated wire loom
  • 
• 1/4 inch eyelet
  • 
• Heat shrink
• Butt connectors

Here is a diagram on what you will need to do.

1. Locate the TIPM connectors C1 and C5 (as shown on the picture above).
   • 
2. Find a brown wire on terminal 40 of the C1 connector.
   1. Cut it 1 inch away from the connector.
   2. Insulate wire from the connector side  with a heat shrink.
   3. Connect the other side to terminal 85 of your bypass fuel pump relay.
3. Find a dark blue/ orange wire on terminal 10 of the C5 connector.
   1. Cut it 1 inch away from the connector.
   2. Insulate wire from the connector side with a heat shrink.
   3. Connect the other side to terminal 87 of your bypass fuel pump relay.
4. Find a pink/ light green wire on terminal 38 the C5 connector.
   1. DO NOT cut this wire.
   2. Solder a new wire to it and connect it to terminal 86 of your bypass fuel pump relay.
5. Connect terminal 30 of your bypass fuel pump relay to the battery positive cable, using 1/4” eyelet.
6. Insulate your work with tape and corrugated wire loom, ziptie any loose wiring, and screw your relay on the body of the car, next to the TIPM.
7. Done