So here’s the project: 1998.5 24v: ECM, PCM, engine harness, pcm harness, engine bay harness, and gauge cluster all 1998.5 from same truck. The cab/ dash harness is a 2001 gasser. My gauges power up fine, shows rpms but nothing else. Gauges appear to pass self test. Codes 920, 921. DOES NOT give me a NO BUS... 

 

I installed my brothers 1999 pcm and no change, took my gauges and pcm to his truck: my pcm works and his gauges work in his truck, my pcm and my gauges work in his truck. His pcm and my gauges work in his truck.... 

 

So: I feel that the 2001 dash harness has different wiring than the 1998.5.... also my head lights don’t work properly. 

 

My question now: can I get a couple wiring diagrams of the main grey plug under the dash so I can move the wiring around to make this work or am I better off trying to get a 1999 dash harness and see if it works with my 1998.5 engine bay harness??? Thanks for any input and sorry for a long first post but I wanted to be thorough. 

Edited July 13, 20195 yr by RyanBelesky
I made mistake

Sign up to be a paid member and there are manuals in the download area.

MONEY Pit .

Yes it is. I like projects and I’m enjoying this one as well. From a bunch of reading that I’ve done, and from just over thinking my situation: I think I wanna try a 1999 dash harness and hope for the best. 

I don't think it wiring but needing to change out both ECM and PCM to match the cluster. The PCM is the master computer, The instrument cluster is what provides the Bus Bias, then The ECM is the second computer. The problem is the PCM is running different software and sending messages the cluster does not understand. This is why there is no "NO BUS" message because it can see the bus but doesn't understand what is being said.

 

Thank you for the reply- but I feel you mis-understood what I wrote tho: the ECM, PCM, & Gauge cluster are all from the 1998.5 24v as most of the wiring. The only wiring that isn’t 1998.5 is the 2001 dash harness. It is somehow different because there is one red with orange wire on the 01 dash harness (if I remember color right) that doesn’t match up with the 1998.5 PDC harness... there may be more but I haven’t dug that deep into it. I did notice that the CCD wires match up (but there’s 3 pair on the 1998.5 and 2 pair on the 2001. Thanks again. 

Ok so after searching and searching on a way to make a 2001 dash harness work with my 1998.5 truck I’ve given up: pulled the dash and will be getting another dash harness.. so out of curiosity does anybody know if all 1998 dash harness are the same?? Mainly because I’m keeping my truck simple with manual windows, manual locks, no over head display, no heated seats, no power mirrors. Just want AC and Heat to work haha. (I’ve already realized I’ll have to use the electronic part of the heater control for my 2001 HVAC- looks simple enough since there’s only 3 wires going from the control to the motor) or should I just change that setup out as well to the cable operated style?? 

Well I figured it out- got a dash from a 1998 gasser and everything works. Even after 10 years of being a dead truck there's no check engine light or warning lights- and yes the bulb works haha. I've been driving the truck around and everything (for the most part) seams great- new track bar, new front KYB shocks going in next, and gotta snug up the steering box a bit. Pretty proud of what I've accomplished this summer on this project and to be able to drive my old truck once again.

There was just too many software and hardware changes to mix and match parts on your truck. This is typically how it goes where thing just don't work out right quite.