GCCUDA

Hopefully someone can help.


I have a 1999 24v that I did a cab Swap using a 1998.5 24v


The headlights are not working after the swap. All the turns signals and running lights are working .


in this swap I used the 1999 under hood wiring from the original truck .
in the cab I used the 1998.5 wiring.


I did notice that the headlight switch is different in the 2 years.
Keep in mind this is a Canadian Truck with day time running lights. Which in fact are Working !
I checked the switch and it is functioning properly (.ie with a test light The power is coming on when it is pulled.) all grounds have been checked and are mounted.

one other note . The headlight's have power going to it when the lights are off one all three wires . I'm note to sure why? but as mentioned the day time running lights come on when the ignition is turned on

Any help is appreciated

cougar

Quite possible the wiring harnesses are different.

GCCUDA

I was under the impression that they would still work because of the plug and play aspect

cougar

Transition model years are always questionable, which the 98/98.5 is. Though they may seem to have the same plugs and sockets, they may very well be wired different. Best thing to do is use all of wiring (connectors and all) from one truck or the other.

torquefan

I have a hazy recollection of, somewhere around that vintage, they made a change from switching the power side to switching the ground side of the headlights. This may or may not be true, and may or may not be your problem, but having the proper wiring diagram in front of you for both the years involved should be a big help in working it out.

VADSLRAM

I know on mine that it is switched on ground side...Not quite sure what the benefit is but it messed with my mind when I went to put in some under hood LED lighting.

GCCUDA

So I looked at the manual of all places and read that the 1999 which was the original . The 99 has from what I see a built in relay . if im wrong please correct me. but the 98 has a completely different harness . could use a diagram for SURE !! on both 98 and 99


So I changed back the original dash over to the 1999 . it is a st dash and wiring but I left the slt wiring harness from the 98 cab for the doors and lighting. We have one connector that goes off the interior harness that mounts to the main harness that has 3 wires coming off it . its at the main junction of connections under the dash where everything joins together .don't know what they control so far . Any ideas ?

GCCUDA

So as of last night I started the truck . Ran for 3 seconds and died . Now its a no start rolling but wont start .


As I mentioned earlier in the forum I had a 1999 engine harness and tried using the 1998 dash harness but had a headlight issue .


So I put the 1999 dash harness back into the truck . Good news that the headlights work . But the no start issue has me stumped. it was running before even with the 1998 dash harness . it was just the headlight issue


Is there any thoughts as to why it started and died and wont start now. its getting fuel . New fuel pump was installed and was working .


?

GCCUDA

SO yesterday as of now the truck has all the original harness in it . And we have the engine rolling over but still no start . put a scanner on it .says p1698 . looked over the ecm all the connections are good . a guy at the dealership says its the vp44 that is failed . How do you test these ecm's to be sure that they are punches ?

nothingbutdarts

Read thru this:


VP44 Diagnostic

GCCUDA

this is worth a look for sure . I will keep you posted . thanks

GCCUDA

SO here is the update . Nothingbutdarts gave me a link about the vp44
I ran all the diagnostics and all the wiring and power is correct to the vp44
I have power and I ground so I decided to try the hardwire to the battery and the pump . The engine rolled and never started .
I though S**T it is the pump . so I sat down and had a beer.


I then decide before I start pulling it all apart give it another go. All of a sudden the engine did a burp!


Waited ten seconds rolled it over . IT STARTED . now every one says its the pump but its not .


Any thoughts .

VADSLRAM

phantom air in the fuel system?
Are you sure all the suction side fittings are tight?

GCCUDA

I'm going to have a second look . Keep in mind it is running when the pump is hardwired to the battery . So I don't believe that that is the issue but I will have a look .