boomer

OK, Here's the problem. About 1 year ago, my 93 D350 started having problems with delayed charging of the battery. When starting on cold mornings the wait to start light would come on with the ignition but wouldn't cycle, it just stayed lit. The heat grid is disconnected. After running the engine enough to warm up the engine compartment, the light would start to flicker along with water in fuel light and the check engine light. These lights would flicker faster and brighter until "bingo", the alternator would engage and the these lights would all go out. The colder the temperature, the longer this process would take. Sometimes up to 15 minutes! Summertime, no problem. Now it's winter again and the problem reappeared. 2 nights ago it was 11 degrees and I went out to start the truck the next morning. Something quit, No wait to start light, no water in fuel light, and no check engine light, no Alternator and no speedometer. Everything else works! No broken wires (that I could find) and all the fuseable links are hot on both ends. Alternator is new and speedometer worked fine the day before. Question is, is the speedometer fed thru the computer?? I'm converting to an external voltage regulator so thats not a problem. But no speedometer is a problem.

A-Poc

Mine's got pretty much the same symptoms. During the summer when you went to start it in the mornings the 'wait to start', 'check engine' and 'water in fuel' light would flicker for a few seconds, then go out. NOW that things are getting proceedingly colder the issue has become worse. When you turn the key when it's cold there will be no 'wait to start', 'check engine' and 'water in fuel' until the keys on for for 1 minute, 2 or whatever. However if you wait it out they will appear and start to flicker and then you'd just need to wait for them to stop, which could lead to SEVERAL minutes of cold frustrating starts. Also, now that it is colder, sometimes when they do stop flickering, it does not necessarily mean that the grid heaters are working. You usually find that out once you turn the key. Mind you she fires right up but she runs very unsteady and rough for 30 seconds or maybe a minute. On top of it all my battery gauge is all over the place and my first relay, towards the front end, clicks and bangs in constant rythm.

I have yet to check any wiring but it is on my 'to do' list.

Mike

paccool

Check the temperature sensor switch in the intake manifold. There are two of them located just behind the intake horn. One is for the heaters, the other is for the KSB (cold start) system on the pump. I don't remember which one is which but you can follow the wire to see which one goes to the fuel shutoff solenoid. That one is for the KSB circut.

Usually when the PCM fails the cruise and AC also act up, but this is not always.

MrHappy

If these symptoms have become (more) prevalent in the cold weather, I would suspect the grid heaters.
Or, more specifically the amount of current that they draw.

I completley removed mine, so I can't really comment on a solution. Sorry.

boomer

Cruise control quit 3 years ago and AC crapped out last summer. Heat grids are disconnected at the solenoids. It's the speedo that baffle's me???

A-Poc

Actually my cruise quit last year, my AC is bypassed and as for the speedo problem... Mine would stop working on and off(could be for 5kms or 50kms) so I replaced my VSS and it has worked ever since.

With my truck it acts like something isn't getting enough charge, hense the clicking, flashing and weird charging of the battery. It could quite possibly be the altenator but I'm curious as to maybe it's a ground or something sketchy somewhere else.

My logic is... since there's enough juice to go from the starter to the battery and start it no problem(Rolls once and fires)... without the grids... then the connection there must be fine... and there must be a problem somewhere else. Wherever that may be, I'm not too sure.

wannadiesel

The speed sensor is powered by the PCM, and there is a speed sensor input to the PCM, but the speedometer is independent of the PCM. It gets the signal straight off the speed sensor. Check the wiring at the speed sensor, and also make sure that the drive adaptor isn't stripped.

Your charging problems make me suspect a crank speed sensor problem. Check the condition of the wiring to it, and also the gap between the sensor and the damper. Should be 0.050, check it with a brass or plastic feeler gauge.

This whole mess may also be caused by a problem with the sensor grounds. There's a big splice that all the sensor grounds join up at, if that splice has corroded it would cause all the sensors not to work. There are two wiring connectors near the back of the engine on the driver's side. One is black. The black wire with the light blue stripe in that black connector is the sensor ground wire, and the splice should be near that connector.

boomer

OK, If I understand you correctly, The speed sensor is powered by the PCM and the speedometer gets the signal straight off the speed sensor, then if the PCM died there would be no power to the speed sensor to send the signal to the speedometer? Is there any way to test the crank speed sensor circut or the output signal from the PCM to the crank speed sensor with a multi meter?? As for a ground problem, it's doubtful, this truck is grounded to the max. I've got backup grounds ran for everything. Ground problems usually aren't seasonal and my problem was definately temperature related.

wannadiesel

You have the first part right. No PCM, no speedo.

You can check the connectors wih a multimeter. One wire should have close to 5 v, one wire should be a good ground, and the third will have stray voltage on it. If you have an oscilloscope you can look at the signal going back to the PCM on the 3rd wire.

The sensor grounds (AKA sensor returns) are not grounded to the engine, they all run to that one splice and then one wire goes into the PCM and is grounded in there. You really ought to find that splice and check it because an open circuit there would make it seem like the PCM was toast.

A-Poc

I looked into mine tonight. I traced some wires and whatnot and I think I've completely solved all my electrical problems. Behind your intake there's a couple solenoids which follow back to the drivers fender into a group of 4. On that same block type thing there are 4 connectors that should just pop off but if they were like mine they were corroded enough that you had to give them a good twist. Once those connectors were cleaned real well and di-electic greased and when I gave the other big four a once over... everything worked just like a top. One of those pop off connectors has a orange with a black stripe down it which is the O/D power wire. That got me to thinking and wha'd ya know... it worked. Mind you I feel a tad embarrased on my part because it was so simple... but nonetheless I can pass people again so who cares