Truck was running fine when I parked it several days ago, but when I went to start it today, I hear a relay clicking repeatedly from somewhere below the radio. thought maybe it was powering the fuel pump, but the pump runs as expected. Eventually the relay stops, but when I try starting, it cranks but not even a hint of starting. Cycling the key sometimes brings the clicking relay back, but not always. But it never starts. No smoke, I have a WTS, tach moves, oil level is good.

I haven't been on here for quite some time, as I rarely drive the truck. I need to find my TorquePro plug-in to check for DTC's and other tests and remember how to use it.
Thanks,
Tom

 

Check the battery connections and condition. Charge the batteries or hook up some GOOD jumper cables.

The buzzing/clicking relay in the dash is indicating low voltage during cranking (not an intended purpose but it's how it goes).

 

The batteries have been charged, and the clicking occurs when initially turning the key on (KOEO), not cranking. I'm used to the low battery voltage / bad cable connection clicking while starting, went through all that a few years ago with a dying starter. Installed a denso back then and replaced all of the OE battery terminals. I was wondering if the relay was trying to power something that was shorted or otherwise electrically failed, and tripping on over-current or such. But I realize now that's not how relays work.

 

Fuel pump and I want to say trailer brake controller relay are behind the dash. I want to say there's a 3rd but can't remember what it's for. You say the pump is running but have you checked that it's pumping? Relays click like that when they don't have good solid connections. Maybe your getting power to the pump but not enough for it to do it's job.

 

Is there a chart or something on here that shows what / where all of the relays are inside the cabin? And aside from a fuel pump one, is there anything that would prevent a start?

 

Sounds like the turn signal flasher if it's KOEO. It will click/buzz when the multifunction switch is bad.

 

Well that one wouldn't surprise me as an upcoming failure, I avoid using turn signals as much as possible as I don't want to replace that switch on the column. But that shouldn't prevent a start. Battery voltage is 11.2V when cranking.

 

ICP is over 700 after cranking, rpm maybe 200 or so, no codes, no smoke. FIPW sits at 0 and occasionally jumps to 6 while KOEO, but mostly 0.

Whatever is clicking when I first turn the key on only does it for a second or so then stops.

 

Unplugged the ICP? That PW isn't right. If it's zero the they aren't firing. They're aren't even being told to.

 

Any codes? TorquePro will miss codes at times. Recommend FORScan or FORScan Lite to pick up possible DTCs to help narrow down the cause.

This is the info I have for 99-01 trucks. The I/P relay block under the radio holds a turn signal relay (large), fuel pump relay, and the trailer running light relay.





Under the dash (driver's knee panel), there is a fuse panel/GEM that holds some relays, but none that should affect starting.





The under hood fuse panel holds the PCM and IDM relays, along with the Blower relay. If you have a steady WTS light with key on, PCM relay is probably good. Could try swapping IDM and Blower relays.




Beside this underhood fuse panel are two relay blocks, one for trailer tow circuits and one for the electronic shift on the fly relays. The owner's manual I have lists these relays in a table, but not their location, which does not help. By testing, they are arranged as follows:




If possible, it could be helpful to see a log from FORScan of your ICP, IPR%, FUELPW, RPM, VPWR while cranking. Sometimes the gauges in TorquePro and FORScan do not react fast enough to catch a quick voltage drop or glitch, but the log will often catch it.

Would like to get a number on your fuel pressure - see if it's steady. In the meantime, you could try swapping the fuel pump and trailer light relays on the I/P relay block to rule out the relay.

As already noted, tired batteries or the cables/connections are suspect when relays chatter.

 

Thank you Jeff,
These were the images I was searching for yesterday morning.in the Tech Folder, but didn't find them. I cleaned and re-tightened the battery terminals yesterday, and charged the batteries overnight, for sme more cranking today. I'll let everyone know what I find.
Thanks again

 

You have a really nice photo of those TS / FP / trailer relays. How the heck do you reach them? I can put a finger on the TS relay, it appears to be the one that clicks - from the vibration - but I can't touch the others, and that's looking through the cup-thrower hole and reaching in through the ashtray hole. Do I have to remove the dash panel??

 

I think you remove the radio

 

Okay, removing the radio gave a much better view, oddly enough the relays are easily reached through the ashtray opening when comfortably seated in the middle and reaching in with your right hand. You just can't see what you're doing. Anyway, it's the fuel pump relay that cycles a lot, but only initially on Key On. It doesn't do it during cranking. Switching relays made no difference. Still troubleshooting, but I have this annoying thing called a job and an employer that expects me to do stuff.

 

The pcm controls the ground, power is spliced off the load side of the pcm relay.