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'87 HCi - does anyone know where the CBHC connector is located? - Fuel System/Carbs - The Lotus Forums Jump to content


'87 HCi - does anyone know where the CBHC connector is located?


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My '80 thru '87 service manual on page 65 section LD shows that the fuel pumps are connected at some point to whats called a CBHC connector.  The problem is that I cant find it!  Its not in m yparts manual and they dont show you were it is.  This is one of the last things I need to test to determine why my fuel pumps will NOT run unless powered by a seperate power supply.  Weve verified voltage throughout most of the system.  The fuel pump relays, the rpm relay, the inertia switch, fuel pump fuses, and even that pesky overspeed module appear to be sending the correct 12 volts while cranking so its not likely any of those items.  I even replaced the RPM relay with a new one just to try it. Car throws a massive spark so its not that.  We have also verified that the connector sockets for these items are not damaged in any way and show correct voltage.

 

This problem started after replacing the battery & tightening the alternator belt which did involve removing the airbox.  Weve checked all of the obvious "maybe you knocked this loose or that loose".  Its beyond that, Im afraid.

 

Like I said, she starts and runs like a beast..... with the fuel pumps wired directly to the battery :)

 

Otherwise, it just cranks but power is not reaching the fuel pumps.  This is really a tough one to sort out!

 

Thanks for any help on that CBHC connector and its location - I need to find that sucker!

 

 

 

 

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I'm probably not the best person to give advice on fuel pumps and Esprit electrics after my S3 decided to develop a fuel pump earth problem when Sparky and Paul Fowler were trying to time it up after a cam belt change but here's two suggestions.

 

 If it has an anti theft device/alarm fitted have you checked it's disarming correctly ?  If it has separate circuits that disable the ignition  the fuel pump etc etc it may be the one for the fuel pump isn't working correctly following the battery change,  The other  thought is, even though you've got 12v  on your meter when you checked the output from the fuel pump relay it may be that the earth from the fuel pump is where the problem is.

Normally Aspirated - and lovin' it!

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Thanks for the replies.  Yes, its the coil box harness connector all right.  I may have found it - under the carpeted shelf over the RH side fuel tank by the cahrcoal cannister.  There are a few conectors there though.  Ill have to investigate.

 

And, yes, I may have a ground problem since neither pump gets any power at key on or during cranking.  It would be very odd for both to have a bad connection..... but they do share a ground, I believe.  Ill check that too.

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Yes, that's where it will be. On the wiring diagrams for my car they still refer to the CBHC even though there's no coil in the luggage compartment relay box and this connector is under the RHS window shelf.

Great - I wonder if they are talking about the connector that plugs into the over speed module?  There are two others in that area that could be it though.  They are not labeled and m,y service manual doesnt help or depict a photo of them.  Hmmm... Ill have to check this out further.  Hopefully I find something and can post back saving some other owners of HCi cars a headache!  :)

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One will be the PHC, 'Pump Harness Connector',(aka FPHC in later manuals) and the other probably the SVC, 'Solenoid Valve Connector'. If it helps identify them the colours of pin 1 on the connectors are:

CBHC - yellow / green
PHC - white / purple
SVC - light green / grey

Edited by sailorbob
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One will be the PHC, 'Pump Harness Connector',(aka FPHC in later manuals) and the other probably the SVC, 'Solenoid Valve Connector'. If it helps identify them the colours of pin 1 on the connectors are:

CBHC - yellow / green

PHC - white / purple

SVC - light green / grey

Great, thanks.  Where in the manual are these connectors shown?  Where are they located on the car?

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The individual pins are just shown on various diagrams. I expect they all are located under the RHS window shelf.

Ok - thanks.  Honestly, I dont think any of that is it.  Here is where we are at:

 

We are getting 12v at the fuse sockets and ran wires directly from those to the power leads on each fuel pump.  Wont start.  nd, we arent getting 12v at the pumps.  There really isnt anything between the fuses and pumps though..... this is crazy.  I dont even know what to do at this point.

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If you have +12v at the pump fuses but not at the pump them you need to check for +12v at the following places:

 

Primary pump - pin 5 of CBHC and pin 3 of PHC (white/green wire)

Secondary pump - pin 4 of CBHC and pin 1 of PHC (white/purple wire)

Edited by sailorbob
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If you have +12v at the pump fuses but not at the pump them you need to check for +12v at the following places:

 

Primary pump - pin 5 of CBHC and pin 3 of PHC (white/green wire)

Secondary pump - pin 4 of CBHC and pin 1 of PHC (white/purple wire)

That makes sense.... but, we did do a test the other night and ran wires directly from the fuse sockets to the pumps, didnt we bypass that CBHC connector by doing so?  And, if thats the case, does the Overspeed module still end up in the chain?  If it does, then I need to get a new one of those to at least eliminate it.

Edited by s2mikey
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Because you ran +12v from the fuses to the fuel pumps you bypassed the CBHC and the PHC. Power is fed from the fuel pump relays via the overspeed module to the fuses so this suggest they are all OK.

Whoa - so the overspeed cant be it either then?  Geesh.... we are running out of things to check!  See why Im stumped here?  The only items left between the pumps and the fuses are the CBHC and the PHC and we bypassed them. 

 

Now what do I do?  :)

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As above, you need to check for +12v at the following places:

 

Primary pump - pin 5 of CBHC and pin 3 of PHC (white/green wire)

Secondary pump - pin 4 of CBHC and pin 1 of PHC (white/purple wire)

 

:)

You're gonna kill me...but didnt our wiring test bypass those connectors since we went straight from the fuel pump fuse sockets to the pumps??  If so, then it has to be something else, right?   If not, Im an idiot and apologize :D

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If you bypassed the CBHC and PHC by running wires directly from the pump fuses to the pumps and the pumps ran then this means the problem is somewhere between the fuses and the pumps. Hence my suggestion to try to isolate the section of wiring and/or connector causing the problem.

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If you bypassed the CBHC and PHC by running wires directly from the pump fuses to the pumps and the pumps ran then this means the problem is somewhere between the fuses and the pumps. Hence my suggestion to try to isolate the section of wiring and/or connector causing the problem.

Ahhh - I explained it wrong then.  When we ran the wires directly to the pumps from the fuse sockets the pumps did NOT run.  The only way they run is to be wired directly(both ground and power) to a 12v source, like the battery.  If they are in any way connected to the cars circuitry, no go deal.  That how we figured the pumps themselves are good.  I also know that the grounding is good, we verified that too.  But, the overspeed module does kill ground if it senses an issue so if its bad then it could be causing them not to run. 

 

See why Im going cookoo here?

 

Thanks for your help though - the CBHC info helps either way.

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OK, best to start at the beginning then.

 

1) Check you are getting +12v at the fuel pump relays from the battery (brown wires).

 

2) Check you are getting +12v out from the fuel pump relays to the overspeed module (white/green and white/purple) at the relays.

 

3) Check you are getting +12v out from the fuel pump relays to the overspeed module (white/green and white/purple) at the module.

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OK, best to start at the beginning then.

 

1) Check you are getting +12v at the fuel pump relays from the battery (brown wires).

 

2) Check you are getting +12v out from the fuel pump relays to the overspeed module (white/green and white/purple) at the relays.

 

3) Check you are getting +12v out from the fuel pump relays to the overspeed module (white/green and white/purple) at the module.

We have done much of this already but I will retest to confirm.  The fact that we get +12v at the fuel pump fuses pretty much gaurantees we got +12 from the relays and over speed module since they are "upstream" from the fuses, I believe.

 

Let me ask you this - I did find out that the Overspeed module kills the ground to the pumps if it detects a failure conditon.  So, if it was a bad unit, then is it possible that what happens is as I crank the car this module is killing the ground to the pumps due to the module being defective?  Just wasnt sure if that made sense or not.  I assumed that since the relays and fuses are getting their +12z that the over speed module had done its job and was out of the loop.  However, maybe Im wrong?

Edited by s2mikey
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If you have +12v at the fuel pump fuses then you should be able to jump from the fuses directly to the pumps and have them run. If they do not run then that would suggest there is high resistance somewhere in the circuit before the fuses limiting the current.

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I am going to order a new OSM today.  We have done enough tests to make it worthwhile to replace this unit.  It is paramount to getting those pumps turned on and if its busted and "senses" an issue it wont power the pumps up at all no matter what else we do.

 

Thats where Im at ;) 

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I would investigate the possibility of high resistance in part (or parts) of the circuit first. Replacing parts without knowing whether they are faulty can soon get expensive.

 

Have you tried bypassing the overspeed module? Disconnect it and bridge some of the pins in the harness connector. The primary fuel pump is white/green both in and out. The secondary fuel pump is white/purple both in and out. Then connect the ground wire (black) to the fuel pump relay coil (pink/purple) to run the fuel pumps.

Edited by sailorbob
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I would investigate the possibility of high resistance in part (or parts) of the circuit first. Replacing parts without knowing whether they are faulty can soon get expensive.

 

Have you tried bypassing the overspeed module? Disconnect it and bridge some of the pins in the harness connector. The primary fuel pump is white/green both in and out. The secondary fuel pump is white/purple both in and out. Then connect the ground wire (black) to the fuel pump relay coil (pink/purple) to run the fuel pumps.

I agree about replacing parts getting costly but this particular unit has to be in question due to what tests have been done already.  It does more than just over speed detection too on my '87. 

 

I will try your described test tonight and see what happens.  When you say bridge, what exactly do you mean?  Take the female connector(the one that runs back into the relay box of the car) and then run a jumper wire from the WG slot to the pink/purple slot on the same connector(female side).

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