[scimitargtc]

pulsing dash/hevac lights since heater O rings (battery fully charged)

98 4.6 - eventually got the O rings for the heater done - realised most of the stuff I undid didn't need undoing/radio/hevac - leaked like a sieve initially but sorted - started her up and the hevac lcd panel and the abs light on the dash are pulsing on and off as if connected to the indicator (flasher) circuit - hopefully that's just a multiplug connection at the main dash panel :sad: & oh there's now a ticking on the left hand bank (when looking at the engine bay) which I hope is NOT a loose liner - hey ho 100 miles in with this one so old one is staying for the time being in case I need major bits from her

 

[scimitargtc]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

58 views no replies... thought had sorted on Sunday cleared all fault codes via MSV extreme tightened battery clamps, sprayed elec cleaner on the 2 connectors under the coolant expansion tank to clear off any coolant when I drained the heater core to fit the O rings - temp and fuel gauge came back on on their own - tonight went to see if there is a simple explanation Y rev counter and speedo don't work - turning ON the main interior light the pulsing stops (map reading lamps make no difference) turn it OFF and the pulsing of the HEVAC panel temp / fuel gauges, and a few other lamps on the central dash - ALL I did was replace the heater O rings why the issue now????? Took care to use a large heavyweight plastic cover on the drivers side when refilling the coolant in case it leaked which it did initially to protect the BECM --- the pulsing I don't understand - it's regular not erratic -- really starting to regret buying this thing - first P38 caused me no issues until the block 'cracked'

 

[mattau]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

Sounds like a short to me. Easy enough with all the wiring behind the dash. When I did my blend motors there was a moment where one of the under seat fuses kept blowing. Also linked in randomly with the interior lights staying on. Removed stereo and tidied up wiring, pushed it carefully back in (as I thought I had done before!), and fuse stopped blowing and interior lights started behaving. Might be some water ingress had contributed to short, but unless there was tons of water it should have dried up by now.

 

[scimitargtc]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

THANKS for a reply - I thought the same - a bit of good old H20 cocking things up -- even swapped over HEVAC panel from the 'Old 'Un' no change and then the speedo dash pack - no change, took radio out - no change - so HAS to be wiring -- will re run MSV extreme checks tomorrow to see if any faults show up

 

[mattau]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

No worries. Hope it's not too hard to resolve. If it wasn't happening before though, then just check the looms etc and should be fine. On previous cars the problem has often been around stereo. Any exposed wire etc, there is normally a fair amount of exposed metal behind dash... Not a good combo! Or when you add water into the mix....!

 

[scimitargtc]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

found some chafed wires on the radio loom - sorted? NOPE turn main interior light on and the pulsing stops still no rev ctr, sometimes getting temp and fuel gauge show getting pee'd off with this radio back out hevac out resting on the centre console -- gotta be an earth or short just gotta be :crybaby2:

 

[scimitargtc]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

ok so another 4 hours and no real way forward - hevac lcd panel flashes on and off, fuel gauge and temp gauage flicker at an exact pace, turn on main interior light and it stops - temp/fuel gauges ok (temp going to wrong side of centre but I think that is part of the elec issue - turn off the light flashing comes back + a very faint dim glow from the main interior light bulb - swapped the light unit in the vain hope - no joy, checked for earth continuity at pin 7 and 17 on the instrument cluster multiplug- that's fine -- just realised the ignition light isn't on either but she starts and runs fine looked at every inch of the cluster wiring loom and part from the chafing I found on the audio part of the loom now kept well out of harms way - cannot believe what I've done when changing the O rings despondent :crybaby2:

 

[mattau]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

If there is flickering at a constant pace, that sounds like maybe electrical supply issue (alternator maybe?). Does pulsing change with engine revs? I have seen a few threads re bad battery etc causing electrical gremlins. What sort of age battery have you got? Might be worth checking earths as well. Maybe you knocked an earth at the engine side of the heater pipes? (I haven't done the o'rings myself so just a guess!) I know RAVE lists earth zones (they probably have a proper technical term....) so might also be worth checking whether any earths under dash that might have been dislodged. I was having an issue with the interior bulb staying dim, and I forget which fuse kept blowing but when it went out the whole dash display died.

 

[scimitargtc]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

flickering remains constant irrespective of revs... looks as if I need to remove as much of the loom as I can BUT it's bugging me that an O ring replacement is causing me so much sodding pain to resolve - don't believe it is the BECM - everything is dry

 

[mattau]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

Might be worth taking a step back! Think back to what you moved/touched whilst doing the o'rings and then think of most likely cause. Keep going back and forth just runs the risk of moving more stuff and upsetting more gremlins! Looking back at your original post, one of the first things you said was the hevac screen pulsing. I noticed on my hevac unit a couple of the plugs are very stiff. They look like they are in but sometimes need that extra "click" into place. Double check dash multi plugs too. I had a dim section on my dash since I got it (figured just a bulb but wasn't high on my priorities). When doing blend motors, I replaced dash and the lights were fine. Maybe coincidence, maybe I knocked something back into place properly! If wires aren't pushed back out the way (I'm thinking cars in general here, not just RR) it can be easy to crimp something when screwing dash panels back in place etc. (Done it myself before!) You probably have already, but I think there is an electrical sticky at the top of the site. Might be worth just reading up on voltage etc and checking you are getting enough current/voltage when it's running.

 

[rtkraken]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

Experienced this exact same symptom in my 95 Classic on a recent trip. Third alternator in four years. Alternator tested SAT on parts store test rig. Replaced the battery (which wasn't exactly dead, but failed charging at store) with new, did entire electrical sticky, checked all grounds, mains, and fuse connections. Finally, with total lack of confidence, renewed the alternator and solved the problem. Start with the electrical sticky and post the results. My money's on the alternator...

 

[scimitargtc]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

no change in pulse frequency with revs - don't believe alt is at fault but will start on the elec sticky tests interesting point mattau makes re dim section of the instrument lcd display - noticed, when I can get it to display that the middle section is dim but on the odd occasion the fuel/temp gauge 'work' the display is as bright as my now broken and languishing 4.0SE Thanks for support here - seen a post from 2008 that had the same issue - wiring loom issue,,, I suppose as 'all' I did were the O rings I'm looking for a quick easy superficial fault - I need to be methodical and work my way round - 1. check every switch light etc 2. check every white connector wires - continuity

 

[mattau]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

Alternator whine through stereo will change with revs (normally) when there is an earth issue, but I just thought pulsing sounds like it could be alternator related. Wasn't sure if it would make the lights pulse faster or not. Re the dash, I would check those multiplugs as you say. Check for any corrosion or bent blades. And that everything is plugged in tight! Keep us posted!

 

[scimitargtc]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

well set off on my task to finally sort this dash instruments / rev counter / speedo - printed the elec diagrams out, highlighted connectors ready to trace, as a contributor said in an early post be logical start at the beginning er so i did -- so that would be checking fuse 1 then wouldn't it Sir er well yes it would and 'er Mmmm Ahhh Oohh darnit yes it had blown presumably when the radio wires had chaffed putting it back in after heater O rings (not that the radio / hevac panel have to come out on a RHD as I've since discovered) replaced with trepidation and SHE LIVES now to put the rest of her back together, fingers crossed the slightly past half way temp was electrical and not another problem and the ticking on the right hand bank is a sticky lifter not a lipped liner - plugs to come out to see it any of them are 'steamed' so fixed but not yet cured THANKS to EVERYONE past and present who made suggestions and were positive and not in anyway deriding of my humble attempts - makes this place THE place to be

 

[rtkraken]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

Gotta love an inexpensive fix! :clap:

 

[scimitargtc]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

yup - physical cost £0.00 (fuse from 'stock') mental cost IMMEASURABLE oh the embarrassment... Anyway back to NOW -- temps fine ,,,,, so pay day she'll get an oil flush and then new oil/filter, + gearbox oil/filter (which I already have) then a good old hand job (so she's all nice and clean before Xmas) Have great breaks everyone

 

[mattau]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

We've all been there mate! So easy to get tied up on the complicated thoughts when sometimes you just have to look at the simple things first! Glad that was the result in this case.

 

[Landy_MN]

Re: pulsing dash/hevac lights since heater O rings (battery fully charged)

well set off on my task to finally sort this dash instruments / rev counter / speedo - printed the elec diagrams out, highlighted connectors ready to trace, as a contributor said in an early post be logical start at the beginning er so i did -- so that would be checking fuse 1 then wouldn't it Sir er well yes it would and 'er Mmmm Ahhh Oohh darnit yes it had blown presumably when the radio wires had chaffed putting it back in after heater O rings (not that the radio / hevac panel have to come out on a RHD as I've since discovered) replaced with trepidation and SHE LIVES now to put the rest of her back together, fingers crossed the slightly past half way temp was electrical and not another problem and the ticking on the right hand bank is a sticky lifter not a lipped liner - plugs to come out to see it any of them are 'steamed' so fixed but not yet cured THANKS to EVERYONE past and present who made suggestions and were positive and not in anyway deriding of my humble attempts - makes this place THE place to be

How friggin weird... just a fuse blown causing strange issues rather than the traditional "one moment something is on and the next moment it's not" typical fuse-blow. Thanks for the thread and post. It helped me solve my "problem". Owning this is going to be interesting. I just took in a '97 p38 on trade. It has all kinds of unknown history (besides carafe), although it seems well cared for in many ways. I couldn't handle the $20 ultra cheapie head unit it came with so I put a CarPlay Kenwood mechless unit in and cleaned up the rats nest of wires. It was absolutely insane with a couple hot-wires of some sort as well. I had an arc twice in the process, one from some strange clear-shelled relay. I plan to go through the process of trying to troubleshoot and integrate the original amps and speakers, but for now, I am patching a new-tech head unit into four crappy "Boss" speakers hack-installed into various interior panels.

Anyways, Cheers and thanks for the help!