Ignition Coils Causing ABS Problem

Bruce Amacker · December 21, 2006

2004 F-450 6.8

I am helping a good client with an ABS problem over the phone. The speedo reads MPH sitting still when you rev the engine up, and ABS light goes on with no codes. I told him to check the charging system for stray AC and other possible wiring issues. He used a scope to select and change the 4 weakest ignition coils, because that's what his dealer "said" to do, reporting a common pattern failure and cited a TSB. We couldn't find a TSB and I've never heard of an ignition coil causing this problem before.

Has anyone else heard of this?

Merry Christmas!

Jim Warman · December 21, 2006

We've seen about 3 that I can recall in the last couple or so years.... I am unsure if the concern is from electrical noise in the system or because of stray RF. Seems to me the techs could feel a bit of a skip in the engine just before the ABS light went on....

HTH

Bruce Amacker · December 22, 2006

Thanks for the response. On this truck, 4 coils made the problem better and 8 coils fixed it totally. Not a cheap fix!

Merry Christmas!

Jim Warman · December 23, 2006

Haven't seen one that extreme yet, but I can say it isn't unimagineable. All of our network busses are nothing more that a big antenna....

It isn't rare to see shielded circuits and all the "old style" wheel speed sensors are twisted pair wiring (a sure sign thst stray RF can be a concern).

Since about 04 or 05, Ford has moved to a different sensor - one is dubbed active and the other passive - I can't for the life of me remember which is which. I do know that the PPTs for the new style has changed drastically. The new style is, AFAIK, not subject to the concerns of RF interference.

DamageINC · December 23, 2006

I've seen Ignition coils cause all sorts of funky problems and this really isn't a big shocker - I'm glad to see that they fixed the problem.

To be honest, we've seen numerous problems lately with the clusters on the Super Duty's (although I think they've all been '05+ models) and the last one I had was traced back to having something welded onto the body/frame of the truck. Need to make sure that the cluster is unplugged when welding anything to these things /forums/images/%%GRAEMLIN_URL%%/smile.gif

Dave

OHNO60 · December 23, 2006

we had an abs lampilluminated and spedo slightly "trembling" at idle. just happend the owner complained about the rough running engine.during powerbalance showed cylinder 3. replaced coil and abs concern resolved. imagine that

Jim Warman · December 24, 2006

Dave, there is a surge protector kinda thing you can get to clamp across the battery terminals... I got one many years ago for the MIG welder I had at the time... Used it faithfully for a long tme but now I prefer to simply unhook both battery cables and pay close attention to my ground placement. A carefully placed vise grip or chain grip will have us ground directly on our parent metal and our workpiece can be safely welded to it.