We have a '02 5.4 (170,000 miles) that has an intermittent problem where the theft light blinks fast, the odometer turns to dashes (------) and the truck will turn over but not start. Originally thought it was a PATS system problem. Tried to read codes while the truck was doing this and the scanner could not receive the codes (error - could not communicate). Is this sounding like a PCM problem? Should I go for a new PCM relay first? Are there any other things that I could check before dropping $$$ on a PCM?

 

This problem sounds somewhat similar to what I have experienced and is described in this thread. It may not be the same issue but sounds very similar. I know my 2000 4.6L has done something exactly like you have described once. I ended up opening the hood and then closing and it then spooled right up. So figured I'd toss that out here to see if it gives anyone else any ideas.

 

I am going to the dealership tomorrow to get a new pcm relay. I figure its worth a shot since this doesn't seem to be an all too common problem. When it first occurred we took the truck to the dealership and they said they couldn't duplicate the problem.

 

Reports here and from dealership about strange instrumentation events during start ups, battery being the problem. Suggest asking the back counter guys there at the dealer, go to the back counter or wholesale guys, they handle the mechanics in the shop and have more knowledge versus the retail counter.

When I was told battery, when my gauges pegged on start-ups, even tho it cranked and started OK, I was skeptical. Fooled me, now everything normal.

 

On my particular truck, the odometer is dashes and theft light blinks. I am not having the gauge sweep problem or any other strange things happening besides the two things mentioned. When I go to the parts counter today I will try to ask.

 

Alright, I got a $13 relay from the dealership. The parts lady knew a lot about parts but not much about the problems bad parts cause. Anyway, the relay is in the truck and we'll see if the problem is fixed. I sure hope so.

 

Mine did it again tonight and I finally figured away to reproduce it. I picked up a set of all the relays that are involved with the PCM just haven't installed them yet. Did it clear of the problem on your pickup jdf150?

 

My truck has been having similar problems, but it continues to run. I hooked up a Genesys scanner up last week to read an ABS code, and it said something about possible low voltage & a battery problem might exist. This will be an interesting thread!

 

Here is what I have been able to do to reproduce the problem. If I punch the accelerator the engine will kind of buck. Then If I release it and do it again it will once again buck then will shut off with the symptoms everyone is describing. I checked the wiring for PDB (Power Distribution Box) and it was clean with no corrosion. I have a few other minor things to fix on the vehicle but from what I have gathered are not related to this problem.

 

I think I may have cured it on my 2000 F150. I swapped the PCM relay in the PDU box under the hood. The pickup now doesn't have any of the odd behavior it was having and what I use to be able to do to reproduce it doesn't. It now nearly goes up RPMs and back down without the hesitation or the cutting of the dash and everything. In the other thread I linked to that was the hopeful solution for the pickup as well. In my case so far it seems to have done it. So just letting everyone else know. Something to check out and a pretty cheap fix.