How to identify a bad main relay on a Honda (PGM-FI)

This is a 1999 Honda Accord with an intermittent no start complaint. Other symptoms include: stalling, long crank times, surging, bucking, poor transmission shifting.
Some quick work with the test light allowed me to zero in on a PGM-FI main relay issue, which was confirmed by a visual inspection on the relay board itself. If you can forgive my soldering work, done through a tiny video camera screen, then you can get an idea of how to repair these relays quickly and easily. Don’t forget to check the Related Videos for a follow up video, detailing the operation of the PGM-FI relay.

Engine Performance Diagnostics chapter 15

Symptoms
- intermittent no start
- no codes present
- possible stalling, long crank times, surging, bucking, poor transmission shifting

Fix
- repaired the PGM-FI main relay

Tests shown
- using scan data to check for a crank signal during cranking
- using the check engine and immobilizer lights to identify possible issues
- how to check for spark using an incandescent test light
- how to check for injection pulse using an incandescent test light
- how to check a fuel pump power feed using an incandescent test light
- how to visually identify a failed solder joint on a PGM-FI main relay
- how to repair a cracked solder joint

Tools used
- Autel MS905 MaxiSys Mini Diagnostic System with Connector Kit - USA Version
https://www.jbtoolsales.com/autel-ms905-maxisys-mini-diagnostic-system-with-vci-and-connector-kit-usa-version#oid=1014_1
- OTC 3633 Mini Circuit Tester
https://www.jbtoolsales.com/otc-3633-mini-circuit-tester#oid=1014_1
- Portasol SP-1K Soldering Iron, Cordless Butane
https://www.jbtoolsales.com/portosol-sp-1k-soldering-iron-cordlss-butane#oid=1014_1

Playlist
- (Chapters 14, 15,16) Fuel Delivery and Fuel Pressure Testing
https://www.youtube.com/playlist?list=PLAFYVCyenqcrstVqfSc1PCbQ1pebuNIO6

Related videos
- Operation and testing of a Honda main relay (PGM-FI) - an SD Premium video
https://youtu.be/QVxOQTSPyGY
- How to test and fix a PGM-FI main relay - Honda/Acura
https://youtu.be/X5Qp-ToR8KA
- Fuel Pump Electrical Circuits Description and Operation
https://youtu.be/Rqtfrx-HeD0
- How to test fuel pressure, injector pulse and spark with basic tools - Honda
https://youtu.be/SUxagOAVS5M
- No Start No Fuel Pressure Troubleshooting - GM 2.2 Ecotec
https://youtu.be/R9PzG_FiNhY

For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium https://www.scannerdanner.com/join-scannerdanner-premium.html There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!

Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.

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